Modified stannic oxide sol, stannic oxide-zirconium oxide composite sol, coating composition and optical element

ABSTRACT

It is to provide a sol useful as a component of a hard coating agent to be applied on the surface of a plastic lens or useful for other applications, and its production process. 
     A sol containing modified metal oxide particles which comprise, as nuclei, colloidal particles (A) being stannic oxide particles or composite particles comprising stannic oxide particles and zirconium oxide particles, containing these oxides in a weight ratio of ZrO 2 :SnO 2  of from 0:1 to 0.50:1 and having particle sizes of from 4 to 50 nm, and as a coating covering the surface of the nuclei, alkylamine-containing Sb 2 O 5  colloidal particles, an oligomer thereof or a mixture thereof (B1), or composite colloidal particles comprising diantimony pentaoxide and silica, an oligomer thereof or a mixture thereof (B2), in a weight ratio of (B)/(A) of from 0.01 to 0.50 based on the weights of the metal oxides, and have particle sizes of from 4.5 to 60 nm. A coating composition containing a silicon-containing substance and the above particles. An optical element covered with the coating composition.

TECHNICAL FIELD

The present invention relates to a sol of modified stannic oxide ormodified stannic oxide-zirconium oxide composite colloidal particleshaving particle sizes of from 4.5 to 60 nm, formed by covering thesurface of tin oxide colloidal particles or stannic oxide-zirconiumoxide composite colloidal particles with alkylamine-containing Sb₂O₅colloidal particles or composite colloidal particles of diantimonypentaoxide and silica, and its production process.

The present invention relates to a coating composition which provides acoating film having excellent warm water resistance and having nodecrease in weather resistance and light resistance even when a vapordeposition film (such as an antireflection film) of an inorganic oxideis provided on the coating film, and an optical element.

BACKGROUND ART

In order to improve the surface of plastic lenses which became usedwidely in recent years, as a component for a hard coating agent to beapplied to said surface, sols of a metal oxide having a high refractiveindex have been used.

A stable sol of tungstic oxide alone has not been known yet, but a solhaving a WO₃:SiO₂:M₂O molar ratio (wherein M is an alkali metal atom oran ammonium group) of 4 to 15:2 to 5:1, obtained by addition of asilicate, has been proposed (e.g. JP-A-54-52686).

A silicate-stannate composite sol having a molar ratio of Si:Sn of 2 to1000:1, has been proposed (e.g. JP-B-50-40119).

A hard coating agent which contains particles of an oxide of a metalsuch as Al, Ti, Zr, Sn or Sb, having particle sizes of from 1 to 300 nm,has been disclosed (e.g. JP-B-63-37142).

A stable sol containing colloidal particles of a modified metal oxidehaving particle sizes of from 4.5 to 60 nm, which comprise colloidalparticles of an oxide of a metal with a valence of 3, 4 or 5, havingparticle sizes of from 4 to 50 nm, as nuclei, and colloidal particles ofa tungstic oxide-stannic oxide composite having a WO₃/SnO₂ weight ratioof from 0.5 to 100 and having particle sizes of from 2 to 7 nm, coveringthe surface of the colloidal particles as nuclei, wherein the content ofthe total metal oxides is from 2 to 50 wt %, has been proposed (e.g.JP-A-3-217230).

A stable sol of a modified SnO₂—ZrO₂ composite which contains particlescomprising colloidal particles of a SnO₂—ZrO₂ composite having a weightratio of ZrO₂/SnO₂ of from 0.02 to 1.0 and having particle sizes of from4 to 50 nm, as nuclei, and colloidal particles of a WO₃—SnO₂ compositehaving a WO₃/SnO₂ weight ratio of from 0.5 to 100 and having particlesizes of from 2 to 7 nm, covering the surface of the colloidal particlesas nuclei, has been proposed (e.g. JP-A-6-24746).

A stable modified metal oxide sol containing particles (C) whichcomprise, as nuclei, colloidal particles (A) of a metal oxide havingprimary particle sizes of from 2 to 60 nm, and a coating (B) comprisingcolloidal particles of an acidic oxide, covering the surface of thenuclei, wherein the particles (C) are contained in a proportion of from2 to 50 wt % as calculated as metal oxides, and having primary particlesizes of from 2 to 100 nm, has been disclosed. Further, a sol whereinthe metal oxide particles as the nuclei are SnO₂ particles or SnO₂—ZrO₂composite colloidal particles, and the coating is made ofalkylamine-containing Sb₂O₅ particles (M/Sb₂O₅ molar ratio of from 0.02to 4.00) has been disclosed (e.g. JP-A-2001-122621).

A process for producing a silicate-antimonate composite sol liquid or asilicate-stannate composite sol liquid, which comprises mixing an alkalisilicate aqueous solution or a silicate sol liquid with an alkaliantimonate aqueous solution or an alkali stannate aqueous solution in amolar ratio of Si:Sb or Si:Sn of 2 to 1,000:1, and subjecting the mixedliquid to cation exchange with an acid form ion exchanger, has beendisclosed (e.g. JP-B-50-40119).

A silica-antimony oxide composite sol having antimony oxide colloidalparticles containing an inorganic silicate compound in an amount of from0.1 to 50 wt % as SiO₂ dispersed in a dispersion medium, has beendisclosed (e.g. JP-B-7-25549).

Plastic molded products are used in a large quantity by virtue of theiradvantageous features such as light weight, good processability and highimpact resistance. On the other hand, they have drawbacks that thehardness is inadequate, and thus they are susceptible to scratching,they are likely to be eroded by a solvent, they are likely to beelectrified and adsorb a dust, and the heat resistance is inadequate.Thus, as compared with inorganic glass molded products, they werepractically inferior for use as lenses for eyeglasses or windowmaterials. Accordingly, it has been proposed to apply a protectivecoating to a plastic molded product. Many compositions have beenproposed as coating compositions to be used for such a protectivecoating.

“A coating composition containing an organic silicon compound or itshydrolysate as the main component (resin component or coatingfilm-forming component)” which was expected to provide a coating film ashard as an inorganic product, has bee used for eyeglass lenses, (e.g.JP-A-52-11261).

This coating composition still does not provide adequate scratchresistance. Accordingly, one having colloidal silica particles added tothe above coating composition has been proposed, which is usedpractically for eyeglass lenses (e.g. JP-A-53-111336).

Heretofore, plastic lenses for eyeglasses have been produced by castingdiethylene glycol bisallyl carbonate in a monomer state, followed bypolymerization. The lenses produced in such a manner have a refractiveindex of about 1.50, which is low as compared with the refractive indexof about 1.52 of glass lenses, and in the case of lenses for shortsighted, there is a problem that the peripheral thickness has to beincreased. Accordingly, in recent years, there has been development ofmonomers having higher refractive indices than the diethylene glycolbisallyl carbonate, and resin materials having high refractive indiceshave been proposed (e.g. JP-A-55-13747, JP-A-56-166214, JP-A-57-23611,JP-A-57-54901, JP-A-59-133211, JP-A-60-199016 and JP-A-64-54021).

For lenses made of such resins having high refractive indices, a methodof using a colloidal dispersion of fine particles of an oxide of a metalsuch as Sb or Ti, for a coating material, has been proposed (e.g.JP-A-62-151801, JP-A-63-275682).

Further, a coating composition comprising a silane coupling agent, and astable modified metal oxide sol containing particles (C) whichcomprises, as nuclei, colloidal particles (A) of a metal oxide havingprimary particle sizes of from 2 to 60 nm, and a coating (B) comprisingcolloidal particles of an acidic oxide, covering the surface of thenuclei, wherein the particles (C) are contained in a proportion of from2 to 50 wt % as calculated as metal oxides, and having primary particlesizes of from 2 to 100 nm, has been disclosed. Further, a coatingcomposition wherein the metal oxide colloidal particles as nuclei areSnO₂ particles or SnO₂—ZrO₂ composite colloidal particles, and thecoating is made of alkylamine-containing Sb₂O₅ particles (M/Sb₂O₅ molarratio of from 0.02 to 4.00) has been disclosed (e.g. JP-A-2001-123115).

DISCLOSURE OF THE INVENTION

A conventional coating composition having a silica sol added thereto,has a problem that the coating film is likely to have interferencefringes which impair the appearance of the lenses. Further, in lenses,an antireflection film (composed of a multilayer structure filmcomprising thin films of inorganic oxides, based on an opticalinterference theory) is formed in many cases, on the coating film. Insuch a case, the antireflection film tends to exhibit, for example, areflection color of extremely pale green, and this reflection colorchanges depending upon the position on the lens surface to formflecking.

Further, a coating composition prepared by using a titanium oxide solhas a problem that the titanium oxide sol has a low compatibility with asilane coupling agent or its hydrolysate, the stability tends to be low,and the coating layer formed by this coating composition tends to bepoor in water resistance and tends to be blued by irradiation withultraviolet rays.

A coating composition prepared by using an antimony oxide sol has aproblem that a coating layer formed from this coating composition willnot have a sufficiently high refractive index, although the stabilityand the compatibility of the antimony oxide sol with a silane couplingagent or its hydrolysate are favorable.

If a conventional metal oxide sol, particularly a cationic metal oxidesol, is used as a component for a hard coating agent, not only thestability of the obtained hard coating agent tends to be insufficient,but also e.g. transparency, adhesion and weather resistance of the curedcoating of the hard coating agent tend to be insufficient. Further, in acase where a Sb₂O₅ sol is used as a component for a hard coating agent,the refractive index of the cured coating will no longer increaseadequately with this Sb₂O₅ sol if the refractive index of the plasticsubstrate for a lens is at least 1.60, since the refractive index ofSb₂O₅ is a level of from 1.65 to 1.70.

The above sol of tungstic oxide as disclosed in JP-A-54-52686 isobtained by adding a silicate to an aqueous solution of tungstic oxideobtainable by subjecting an aqueous solution of a tungstate to cationexchange. However, the sol is stable only in a strong acidic condition,and its effect to increase the refractive index of the coating film issmall when used as a component for a hard coating agent.

The above silicate-stannate composite sol as disclosed in JP-B-50-40119is obtained by subjecting a mixed aqueous solution of an alkali silicateand an alkali stannate to cation exchange. However, its effect toincrease the refractive index of the coating film is also small whenused as a component for a hard coating agent.

The above modified metal oxide sol as disclosed in JP-A-3-217230 has arefractive index of at least 1.7, is stable, can be used as a componentfor a hard coating agent for plastic lenses, and substantially satisfiesperformances required for a hard coat film, such as scratch resistance,transparency, adhesion, water resistance and weather resistance.

The above modified stannic oxide-zirconium oxide sol as disclosed inJP-A-6-24746 has a refractive index of at least 1.7, is stable, can beused as a component for a hard coating agent for plastic lenses, andsubstantially satisfies performances required for a hard coat film, suchas scratch resistance, transparency and adhesion.

It is an object of the present invention to provide a metal oxide solwhich is a stable modified stannic oxide or modified stannicoxide-zirconium oxide sol, which further improves scratch resistance,transparency, adhesion, water resistance, weather resistance, etc. of ahard coat film employing the modified metal oxide as disclosed inJP-A-3-217230 or JP-A-6-24746, and which is stable in a wide pH range,and which can be mixed with a coating material for a hard coat film as acomponent to improve performance of a hard coat film to be formed on thesurface of a plastic lens.

Further, it is an object of the present invention to provide a coatingcomposition which provides a coating film free from interference fringesor flecking in reflection colors, on a plastic molded product having amoderate to high refractive index of nd=1.54 to 1.70, and an opticalelement.

Still further, it is an object of the present invention to provide acoating composition for plastic molded products, which is excellent inscratch resistance, surface hardness, abrasion resistance, flexibility,transparency, antistatic properties, dyeability, heat resistance, waterresistance, chemical resistance, etc., and an optical element.

Accordingly, the present invention provides the following.

-   1. A sol containing modified metal oxide particles which comprise,    as nuclei, colloidal particles (A) being stannic oxide particles or    composite particles comprising stannic oxide particles and zirconium    oxide particles, containing these oxides in a weight ratio of    ZrO₂:SnO₂ of from 0:1 to 0.50:1 and having particle sizes of from 4    to 50 nm, and as a coating covering the surface of the nuclei,    alkylamine-containing Sb₂O₅ colloidal particles having a M/Sb₂O₅    molar ratio (M represents an amine molecule) of from 0.02 to 4.00,    an oligomer thereof or a mixture thereof (B1), in a weight ratio of    (B1)/(A) of from 0.01 to 0.50 based on the weights of the metal    oxides, and have particle sizes of from 4.5 to 60 nm.-   2. The sol according to the above 1, wherein the colloidal    particles (A) are stannic oxide particles.-   3. The sol according to the above 1, wherein the colloidal    particles (A) are composite colloidal particles comprising stannic    oxide particles and zirconium oxide particles in a weight ratio of    ZrO₂:SnO₂ of from 0.05:1 to 0.50:1-   4. A sol containing modified metal oxide particles which comprise,    as nuclei, colloidal particles (A) being stannic oxide particles or    composite particles comprising stannic oxide particles and zirconium    oxide particles, containing these oxides in a weight ratio of    ZrO₂:SnO₂ of from 0:1 to 0.50:1 and having particle sizes of from 4    to 50 nm, and as a coating covering the surface of the nuclei,    composite colloidal particles comprising diantimony pentaoxide and    silica having a SiO₂/Sb₂O₅ molar ratio of from 0.55 to 55, an    oligomer thereof or a mixture thereof (B2), in a weight ratio of    (B2)/(A) of from 0.01 to 0.50 based on the weights of the metal    oxides, and have particle sizes of from 4.5 to 60 nm.-   5. The sol according to claim 4, wherein the colloidal particles (A)    are stannic oxide particles.-   6. The sol according to the above 4, wherein the colloidal    particles (A) are composite colloidal particles comprising stannic    oxide particles and zirconium oxide particles in a weight ratio of    ZrO₂:SnO₂ of from 0.05:1 to 0.50:1-   7. A process for producing the sol as defined in the above 1 or 2,    which comprises the following steps (a1), (b1) and (c1):

step (a1): a step of preparing a stannic oxide aqueous sol containingstannic oxide colloidal particles having particle sizes of from 4 to 50nm at a SnO₂ concentration of from 1 to 50 wt %,

step (b1): a step of mixing the stannic oxide aqueous sol obtained inthe above step (a1), with an aqueous medium containingalkylamine-containing Sb₂O₅ colloidal particles having a M/Sb₂O₅ molarratio (M represents an amine molecule) of from 0.02 to 4.00, an oligomerthereof or a mixture thereof, in a weight ratio of Sb₂O₅/SnO₂ ascalculated as metal oxides of from 0.01 to 0.50, and

step (c1): a step of aging the aqueous medium obtained in step (b1) at atemperature of from 20 to 300° C. for from 0.1 to 50 hours.

-   8. A process for producing the sol as defined in the above 1 or 3,    which comprises the following steps (a2), (b2), (c2) and (d3):

step (a2): a step of mixing a stannic oxide aqueous sol having particlesizes of from 4 to 50 nm and having a SnO₂ concentration of from 0.5 to50 wt %, with an aqueous solution of an oxyzirconium salt having aconcentration of from 0.5 to 50 wt % as calculated as ZrO₂, in a weightratio of ZrO₂/SnO₂ of from 0.05 to 0.50, and heating the obtained mixedliquid at a temperature of from 60 to 100° C. for from 0.1 to 50 hoursto prepare a stannic oxide-zirconium oxide composite aqueous sol havingparticle sizes of from 4 to 50 nm,

step (b2): a step of mixing the stannic oxide-zirconium oxide compositeaqueous sol obtained in step (a2), with an aqueous medium containingalkylamine-containing Sb₂O₅ colloidal particles having a M/Sb₂O₅ molarratio (M represents an amine molecule) of from 0.02 to 4.00, an oligomerthereof or a mixture thereof, in a weight ratio of Sb₂O₅/(SnO₂+ZrO₂) offrom 0.01 to 0.50 as calculated as metal oxides,

step (c2): a step of aging the aqueous medium obtained in step (b2) at atemperature of from 20 to 300° C. for from 0.1 to 50 hours, and

step (d2): a step of bringing the modified stannic oxide-zirconium oxidecomposite aqueous sol obtained in step (c2) into contact with an anionexchanger to remove anions present in the sol.

-   9. A process for producing the sol as defined in the above 1 or 2,    which comprises the following steps (a3), (b3) and (c3):

step (a3): a step of preparing a stannic oxide aqueous sol subjected toa hydrothermal treatment at a temperature of from 100 to 300° C., andhaving particle sizes of from 4 to 50 nm and a SnO₂ concentration offrom 0.5 to 50 wt %,

step (b3): a step of mixing the stannic oxide aqueous sol obtained inthe above step (a3), with an aqueous medium containingalkylamine-containing Sb₂O₅ colloidal particles having a M/Sb₂O₅ molarratio (M represents an amine molecule) of from 0.02 to 4.00, an oligomerthereof or a mixture thereof, in a weight ratio of Sb₂O₅/SnO₂ ascalculated as metal oxides of from 0.01 to 0.50, and

step (c3): a step of aging the aqueous medium obtained in step (b3) at atemperature of from 20 to 300° C. for from 0.1 to 50 hours.

-   10. A process for producing the sol as defined in the above 1 or 3,    which comprises the following steps (a4), (b4), (c4) and (d4):

step (a4): a step of mixing a stannic oxide aqueous sol subjected to ahydrothermal treatment at a temperature of from 100 to 300° C., andhaving particle sizes of from 4 to 50 nm and a SnO₂ concentration offrom 0.5 to 50 wt %, with an aqueous solution of an oxyzirconium salthaving a concentration of from 0.5 to 50 wt % as calculated as ZrO₂, ina weight ratio of ZrO₂/SnO₂ of from 0.05 to 0.50, and heating theobtained mixed liquid at a temperature of from 60 to 100° C. for from0.1 to 50 hours to prepare a stannic oxide-zirconium oxide compositeaqueous sol having particle sizes of from 4 to 50 nm,

step (b4): a step of mixing the stannic oxide-zirconium oxide compositeaqueous sol obtained in step (a4), with an aqueous medium containingalkylamine-containing Sb₂O₅ colloidal particles having a M/Sb₂O₅ molarratio (M represents an amine molecule) of from 0.02 to 4.00, an oligomerthereof or a mixture thereof, in a weight ratio of Sb₂O₅/(SnO₂+ZrO₂) offrom 0.01 to 0.50 as calculated as metal oxides,

step (c4): a step of aging the aqueous medium obtained in step (b4) at atemperature of from 20 to 300° C. for from 0.1 to 50 hours, and

step (d4): a step of bringing the modified stannic oxide-zirconium oxidecomposite aqueous sol obtained in step (c4) into contact with an anionexchanger to remove anions present in the sol.

-   11. A process for producing the sol as defined in the above 4 or 5,    which comprises the following steps (a5), (b5) and (c5):

step (a5): a step of preparing a stannic oxide aqueous sol containingstannic oxide colloidal particles having particle sizes of from 4 to 50nm at a SnO₂ concentration of from 1 to 50 wt %,

step (b5): a step of mixing the stannic oxide aqueous sol obtained inthe above step (a5), with an aqueous medium containing compositecolloidal particles of diantimony pentaoxide and silica having aSiO₂/Sb₂O₅ molar ratio of from 0.55 to 55, an oligomer thereof or amixture thereof, in a weight ratio of (Sb₂O₅+SiO₂)/(SnO₂) as calculatedas metal oxides of from 0.01 to 0.50, and

step (c5): a step of aging the aqueous medium obtained in step (b5) at atemperature of from 20 to 300° C. for from 0.1 to 50 hours.

-   12. A process for producing the sol as defined in the above 4 or 6,    which comprises the following steps (a6), (b6), (c6) and (d6):

step (a6): a step of mixing a stannic oxide aqueous sol having particlesizes of from 4 to 50 nm and a SnO₂ concentration of from 0.5 to 50 wt%, with an aqueous solution of an oxyzirconium salt having aconcentration of from 0.5 to 50 wt % as calculated as ZrO₂, in a weightratio of ZrO₂/SnO₂ of from 0.05 to 0.50, and heating the obtained mixedliquid at a temperature of from 60 to 100° C. for from 0.1 to 50 hoursto prepare a stannic oxide-zirconium oxide composite aqueous sol havingparticle sizes of from 4 to 50 nm,

step (b6): a step of mixing the stannic oxide-zirconium oxide compositeaqueous sol obtained in step (a6), with an aqueous medium containingcomposite colloidal particles of diantimony pentaoxide and silica havinga SiO₂/Sb₂O₅ molar ratio of from 0.55 to 55, an oligomer thereof or amixture thereof, in a weight ratio of (Sb₂O₅+SiO₂)/(SnO₂+ZrO₂) ascalculated as metal oxides of from 0.01 to 0.50,

step (c6): a step of aging the aqueous medium obtained in step (b6) at atemperature of from 20 to 300° C. for from 0.1 to 50 hours, and

step (d6): a step of bringing the modified stannic oxide-zirconium oxidecomposite aqueous sol obtained in step (c6) into contact with an anionexchanger to remove anions present in the sol.

-   13. A process for producing the sol as defined in the above 4 or 5,    which comprises the following steps (a7), (b7) and (c7):

step (a7): a step of preparing a stannic oxide aqueous sol subjected toa hydrothermal treatment at a temperature of from 100 to 300° C., andhaving particle sizes of from 4 to 50 nm and a SnO₂ concentration offrom 0.5 to 50 wt %,

step (b7): a step of mixing the stannic oxide aqueous sol obtained inthe above step (a7), with an aqueous medium containing compositecolloidal particles of diantimony pentaoxide and silica having aSiO₂/Sb₂O₅ molar ratio of from 0.55 to 55, an oligomer thereof or amixture thereof, in a weight ratio of (Sb₂O₅+SiO₂)/(SnO₂) as calculatedas metal oxides of from 0.01 to 0.50, and

step (c7): a step of aging the aqueous medium obtained in step (b7) at atemperature of from 20 to 300° C. for from 0.1 to 50 hours.

-   14. A process for producing the sol as defined in the above 4 or 6,    which comprises the following steps (a8), (b8), (c8) and (d8):

step (a8): a step of mixing a stannic oxide aqueous sol subjected to ahydrothermal treatment at a temperature of from 100 to 300° C., andhaving particle sizes of from 4 to 50 nm and a SnO₂ concentration offrom 0.5 to 50 wt %, with an aqueous solution of an oxyzirconium salthaving a concentration of from 0.5 to 50 wt % as calculated as ZrO₂, ina weight ratio of ZrO₂/SnO₂ of from 0.05 to 0.50, and heating theobtained mixed liquid at a temperature of from 60 to 100° C. for from0.1 to 50 hours to prepare a stannic oxide-zirconium oxide compositeaqueous sol having particle sizes of from 4 to 50 nm,

step (b8): a step of mixing the stannic oxide-zirconium oxide compositeaqueous sol obtained in step (a8), with an aqueous medium containingcomposite colloidal particles of diantimony pentaoxide and silica havinga SiO₂/Sb₂O₅ molar ratio of from 0.55 to 55, an oligomer thereof or amixture thereof, in a weight ratio of (Sb₂O₅+SiO₂)/(SnO₂+ZrO₂) ascalculated as metal oxides of from 0.01 to 0.50,

step (c8): a step of aging the aqueous medium obtained in step (b8) at atemperature of from 20 to 300° C. for from 0.1 to 50 hours, and

step (d8): a step of bringing the modified stannic oxide-zirconium oxidecomposite aqueous sol obtained in step (c8) into contact with an anionexchanger to remove anions present in the sol.

-   15. A coating composition containing the following components (S)    and (T1):

component (S): at least one silicon-containing substance selected fromthe group consisting of organic silicon compounds of the formulae (I)and (II), and hydrolysates thereof:(R¹)_(a)(R³)_(b)Si(OR²)_(4−(a+b))  (I)wherein each of R¹ and R³ is an alkyl group, an aryl group, ahalogenated alkyl group, a halogenated aryl group, an alkenyl group, oran organic group having an epoxy group, an acryloyl group, amethacryloyl group, a mercapto group, an amino group or a cyano group,which is bonded to the silicon atom by a Si—C bond, R² is a C₁₋₈ alkylgroup, an alkoxyalkyl group or an acyl group, and each of a and b is aninteger of 0, 1 or 2, provided that a+b is an integer of 0, 1 or 2,[(R⁴)_(c)Si(OX)_(3−c)]₂Y  (II)wherein R⁴ is a C₁₋₅ alkyl group, X is a C₁₋₄ alkyl group or an acylgroup, Y is a methylene group or a C₂₋₂₀ alkylene group, and c is aninteger of 0 or 1;

component (T1): modified metal oxide particles, which comprise, asnuclei, colloidal particles (A) being stannic oxide particles orcomposite particles comprising stannic oxide particles and zirconiumoxide particles, containing these oxides in a weight ratio of ZrO₂:SnO₂of from 0:1 to 0.50:1 and having particle sizes of from 4 to 50 nm, andas a coating covering the surface of the nuclei, alkylamine-containingSb₂O₅ colloidal particles having a M/Sb₂O₅ molar ratio (M represents anamine molecule) of from 0.02 to 4.00, an oligomer thereof or a mixturethereof (B1), in a weight ratio of (B1)/(A) of from 0.01 to 0.50 basedon the weights of the metal oxides, and have particle sizes of from 4.5to 60 nm.

-   16. The coating composition according to the above 15, wherein the    colloidal particles (A) are stannic oxide particles.-   17. The coating composition according to the above 15, wherein the    colloidal particles (A) are composite colloidal particles comprising    stannic oxide particles and zirconium oxide particles in a weight    ratio of ZrO₂:SnO₂ of from 0.05:1 to 0.50:1-   18. The coating composition according to any one of the above 15 to    17, wherein the coating (B1) in the component (T1) further contains    an alkylamine-containing silica.-   19. A coating composition containing the following components (S)    and (T2):

component (S): at least one silicon-containing substance selected fromthe group consisting of organic silicon compounds of the formulae (I)and (II), and hydrolysates thereof:(R¹)_(a)(R³)_(b)Si(OR²)_(4−(a+b))  (I)wherein each of R¹ and R³ is an alkyl group, an aryl group, ahalogenated alkyl group, a halogenated aryl group, an alkenyl group, oran organic group having an epoxy group, an acryloyl group, amethacryloyl group, a mercapto group, an amino group or a cyano group,which is bonded to the silicon atom by a Si—C bond, R² is a C₁₋₈ alkylgroup, an alkoxyalkyl group or an acyl group, and each of a and b is aninteger of 0, 1 or 2, provided that a+b is an integer of 0, 1 or 2,[(R⁴)_(c)Si(OX)_(3−c)]₂Y  (II)wherein R⁴ is a C₁₋₅ alkyl group, X is a C₁₋₄ alkyl group or an acylgroup, Y is a methylene group or a C₂₋₂₀ alkylene group, and c is aninteger of 0 or 1;

component (T2): modified metal oxide particles, which comprise, asnuclei, colloidal particles (A) being stannic oxide particles orcomposite particles comprising stannic oxide particles and zirconiumoxide particles, containing these oxides in a weight ratio of ZrO₂:SnO₂of from 0:1 to 0.50:1 and having particle sizes of from 4 to 50 nm, andas a coating covering the surface of the nuclei, composite colloidalparticles comprising diantimony pentaoxide and silica having aSiO₂/Sb₂O₅ molar ratio of from 0.55 to 55, an oligomer thereof or amixture thereof (B2), in a weight ratio of (B2)/(A) of from 0.01 to 0.50based on the weights of metal oxides, and have particle sizes of from4.5 to 60 nm.

-   20. The coating composition according to the above 19, wherein the    colloidal particles (A) are stannic oxide particles.-   21. The coating composition according to the above 19, wherein the    colloidal particles (A) are composite colloidal particles comprising    stannic oxide particles and zirconium oxide particles in a weight    ratio of ZrO₂:SnO₂ of from 0.05:1 to 0.50:1.-   22. The coating composition according to any one of the above 19 to    21, wherein the coating (B2) in the component (T1) further contains    an alkylamine-containing silica.-   23. The coating composition according to any one of the above 15 to    22, wherein the component (A) is at least one silicon-containing    substance selected from the group consisting of the organic silicon    compound of the formula (I) and a hydrolysate thereof.-   24. The coating composition according to any one of the above 15 to    23, which contains at least one curing catalyst selected from the    group consisting of a metal salt, a metal alkoxide and a metal    chelate compound.-   25. An optical element comprising an optical substrate and a cured    film formed from the coating composition as defined in any one of    the above 15 to 24 on the surface of the optical substrate.-   26. The optical element according to the above 25, which further has    an antireflection film formed on its surface.

EFFECTS OF THE INVENTION

According to the present invention, by the effect of a coatingcomprising an alkali antimonate, an alkali component-containingdiantimony pentaoxide colloid or its oligomer, or a coating having asilica component further added thereto, or a coating comprising adiantimony pentaoxide-silica composite colloid, an oligomer thereof or amixture thereof, various defects (dispersibility, weather resistance,long-term stability, compatibility with a hard coating agent, bondingproperties) of a conventional metal oxide colloid can be reduced, and anexcellent modified metal oxide can be obtained. By using the modifiedstannic oxide and/or stannic oxide-zirconium oxide composite colloid ofthe present invention as a hard coating agent component, problems ofyellowing due to irradiation with ultraviolet rays, and film hardness,water resistance, moisture resistance and compatibility, which arisewhen a conventional metal oxide sol is used, can be overcome.

According to the present invention, a stable sol of colloidal particlesof a modified metal oxide having favorable water resistance and weatherresistance is provided, and a sol which can be mixed, as a component toimprove performance of a hard coat film to be applied on the surface ofa plastic lens, with a coating composition for the hard coat film can beprovided.

The sol of metal oxide colloidal particles having their surface modifiedobtained by the present invention is colorless and transparent, and adry coating film obtained from the sol has a refractive index of fromabout 1.75 to about 1.92, has high bonding strength and hardness, andhas favorable weather resistance, antistatic properties, heatresistance, abrasion resistance, etc. Further, particularly the weatherresistance and the moisture resistance remarkably improve as comparedwith a conventional one.

The sol of the present invention is stable at a pH of from 1 to 11,preferably from 1.5 to 10, and provides stability sufficient as anindustrial product.

Since the colloidal particles of the sol of the present invention arenegatively charged, the sol has favorable miscibility with e.g. a solcomprising other negatively charged colloidal particles, and it can bestably mixed with, for example, a silica sol, a diantimony pentaoxidesol, an anionic or nonionic surfactant, an aqueous solution of e.g.polyvinyl alcohol, an anionic or nonionic resin emulsion, water glass,an aqueous solution of e.g. aluminum phosphate, a hydrolysate solutionof ethyl silicate, or a silane coupling agent such as γ-glycidoxytrimethoxysilane or a hydrolysate solution thereof.

A cured film obtained from the coating composition of the presentinvention constitute a coating layer having improved scratchedresistance, surface hardness, abrasion resistance, transparency, heatresistance, light resistance and weather resistance, particularly waterresistance. Further, the cured film has favorable adhesive propertieswith a metal deposited film or an antireflection film (made of e.g. aninorganic oxide or a fluoride) to be formed on the coating layer.

The optical element of the present invention is excellent in scratchresistance, surface hardness, abrasion resistance, transparency, heatresistance, light resistance and weather resistance, particularly waterresistance, and further, which has favorable appearance with hightransparency without interference fringes even when coating is appliedon an element having a high refractive index of at least 1.54.

BEST MODE FOR CARRYING OUT THE INVENTION

The present invention provides a sol containing modified metal oxideparticles which comprise, as nuclei, colloidal particles (A) beingstannic oxide particles or composite particles comprising stannic oxideparticles and zirconium oxide particles, containing these oxides in aweight ratio of ZrO₂:SnO₂ of from 0:1 to 0.50:1 and having particlesizes of from 4 to 50 nm, and as a coating covering the surface of thenuclei, alkylamine-containing Sb₂O₅ colloidal particles having a M/Sb₂O₅molar ratio (M represents an amine molecule) of from 0.02 to 4.00, anoligomer thereof or a mixture thereof (B1), in a weight ratio of(B1)/(A) of from 0.01 to 0.50 based on the weights of the metal oxides,and have particle sizes of from 4.5 to 60 nm.

Further, the present invention provides a sol containing modified metaloxide particles which comprise, as nuclei, colloidal particles (A) beingstannic oxide particles or composite particles comprising stannic oxideparticles and zirconium oxide particles, containing these oxides in aweight ratio of ZrO₂:SnO₂ of from 0:1 to 0.50:1 and having particlesizes of from 4 to 50 nm, and as a coating covering the surface of thenuclei, composite colloidal particles comprising diantimony pentaoxideand silica having a SiO₂/Sb₂O₅ molar ratio of from 0.55 to 55, anoligomer thereof or a mixture thereof (B2), in a weight ratio of(B2)/(A) of from 0.01 to 0.50 based on the weights of the metal oxides,and have particle sizes of from 4.5 to 60 nm.

The particle sizes in the above sol are represented by the particlesizes as observed by an electron microscope.

The stannic oxide colloidal particles as nucleus particles (A) to beused for production of the sol of the present invention can easily bemade in the form of a sol of colloidal particles having particle sizesat a level of from 4 to 50 nm, by a known method such as an ion exchangemethod, a peptization method, a hydrolysis method or a reaction method.

The above ion exchange method may, for example, be a method of treatinga stannate such as sodium stannate with a hydrogen form cation exchangeresin, or a method of treating a stannic salt such as stannic chlorideor stannic nitrate with a hydroxyl group form anion exchange resin. Thepeptization method may, for example, be a method of washing a stannichydroxide gel obtained by neutralizing a stannic salt with a base or byneutralizing stannic acid with hydrochloric acid, followed bypeptization with an acid or a base. The hydrolysis method may, forexample, be a method of hydrolyzing a tin alkoxide, or a method ofhydrolyzing a basic stannic chloride basic salt under heating, followedby removal of an unnecessary acid. The above reaction method may, forexample, be a method of reacting a metal tin powder with an acid.

The stannic oxide aqueous sol produced by the above method may be usedas it is, or may be used after subjected to a hydrothermal treatment ata temperature of from 100 to 300° C.

As the hydrothermal treatment, for example, the above stannic oxideaqueous sol is put in an autoclave, and a treatment is carried out at atemperature of from 100 to 300° C. for from 0.1 to 200 hours.

The medium of such a stannic oxide sol may be either water or ahydrophilic organic solvent, however, preferred is an aqueous solemploying water as a medium. Further, the pH of the sol is preferablysuch a pH as to stabilize the sol, and usually preferably at a level offrom 0.2 to 11.5. The stannic oxide sol may contain an optionalcomponent such as an alkaline substance, an acidic substance or anoxycarboxylic acid for the purpose of stabilizing the sol, so long asthe object of the present invention will be achieved. The concentrationof the stannic oxide sol to be used is preferably at a level of from 0.5to 50 wt % as stannic oxide, however, the concentration is preferablylower, and preferably from 1 to 30 wt %.

The stannic oxide-zirconium oxide composite sol as the nucleus particles(A) to be used for production of the sol of the present invention can beobtained by steps of mixing an oxyzirconium salt with the above stannicoxide sol in a ZrO₂/SnO₂ weight ratio of from 0.05 to 0.5 at from 5 to100° C. for from 0.5 to 3 hours, and then heating the mixture at from 60to 100° C. for from 0.1 to 50 hours.

The stannic oxide sol to be used may be either a sol preliminarilysubjected to a hydrothermal treatment or a sol not subjected to ahydrothermal treatment.

The oxyzirconium salt to be used may, for example, be zirconiumoxychloride, zirconium oxynitrate, zirconium oxysulfate, a zirconiumoxyhydroxy acid such as zirconium oxyacetate, or zirconium oxycarbonate.Such an oxyzirconium salt may be used as a solid or an aqueous solution,however, it is preferably used in the form of an aqueous solution havinga concentration of ZrO₂ of from 0.5 to 50 wt %, preferably at a level offrom 0.5 to 30 wt %. A water-insoluble salt such as zirconiumoxycarbonate can be used when stannic oxide is in the form of an acidsol.

The stannic oxide sol is particularly preferably an alkaline solstabilized by an organic base such as an amine, and mixing with anoxyzirconium salt is carried out at a temperature of from 5 to 100° C.,preferably from room temperature (20° C.) to 60° C. For the mixing, anoxyzirconium salt may be added to the stannic oxide sol with stirring,or the stannic oxide sol may be added to an oxyzirconium salt aqueoussolution with stirring, but the latter is preferred. The mixing has tobe carried out sufficiently, preferably for from 0.5 to 3 hours.

The alkylamine-containing diantimony pentaoxide colloid, an oligomerthereof or a mixture thereof (B1) to be used for a coating sol in thepresent invention may be obtained by the following methods (oxidationmethod, acid decomposition method, etc.). The acid decomposition methodmay, for example, be a method of reacting an alkali antimonate with aninorganic acid, followed by peptization with an amine (JP-A-60-41536,JP-A-61-227918, JP-A-2001-123115), and the oxidation method may, forexample, be a method of oxidizing diantimony trioxide with hydrogenperoxide in the coexistence of an amine or an alkali metal(JP-B-57-11848, JP-A-59-232921) or a method of oxidizing diantimonytrioxide with hydrogen peroxide and adding an amine or an alkali metal.

The amine in the above amine-containing diantimony pentaoxide colloid,an oligomer thereof or a mixture thereof, may, for example, be ammonium,a quaternary ammonium or a water soluble amine. Preferably, it may, forexample, be an alkylamine such as isopropylamine, diisopropylamine,n-propylamine or diisobutylamine, an aralkylamine such as benzylamine,an alicyclic amine such as piperidine, an alkanolamine such asmonoethanolamine or triethanolamine, or a quaternary ammonium such astetramethylammonium hydroxide. It is particularly preferablydiisopropylamine or diisobutylamine. The molar ratio of the alkalicomponent to diantimony pentaoxide in the amine-containing diantimonypentaoxide colloid is preferably from 0.02 to 4.00 as M/Sb₂O₅. If it issmaller than this, the colloid to be obtained tends to be poor instability, and if it is too high, a dry coating film to be obtained byusing such a sol tends to have low water resistance, such beingunfavorable practically.

The amine-containing diantimony pentaoxide colloidal particles, anoligomer thereof or a mixture thereof (B1) are fine colloidal particlesof diantimony pentaoxide, an oligomer thereof or a mixture thereof. Withrespect to the colloidal particles, particles of at most 20 nm could beobserved by an electron microscope. The oligomer is a polymer and cannot be observed by an electron microscope. In the present invention, thecolloidal particles (A) have particle sizes of from 4 to 50 nm, and themodified metal oxide particles obtained by covering with (B1) haveparticle sizes of from 4.5 to 60 nm. The increase in the particle sizecorresponds to the negatively charged colloidal particles, an oligomerthereof or a mixture thereof (B1) which are chemically bonded to thesurface of the positively charged colloidal particles (A) and therebycover the colloidal particles (A).

The amine component is preferably an alkylamine salt of e.g.diisopropylamine, and the molar ratio of amine/Sb₂O₅ is from 0.02 to4.00.

With respect to the above coating, alkylamine-containing silicaparticles may further be added to the amine-containing diantimonypentaoxide colloidal particles, an oligomer thereof or a mixturethereof.

A composite colloid comprising diantimony pentaoxide and silica, anoligomer thereof or a mixture thereof (B2) to be used for a coating solin the present invention can be obtained by the following known method(e.g. JP-B-50-40119). Namely, it can be obtained by mixing an alkalisilicate aqueous solution or a silicic acid sol liquid with an alkaliantimonate aqueous solution, followed by cation exchange with a cationexchange resin.

As the antimony material, preferably a potassium antimonate aqueoussolution may be used. As the silica material, sodium silicate, potassiumsilicate or active silicic acid obtained by cation exchange of each ofthem, may be used. The molar ratio of SiO₂/Sb₂O₅ is from 0.55 to 55.

The composite colloid comprising diantimony pentaoxide and silica, anoligomer thereof or a mixture thereof (B2) is fine composite colloidcomprising diantimony pentaoxide and silica, an oligomer thereof or amixture thereof. With respect to the colloidal particles, particles ofat most 5 nm could be observed by an electron microscope. The oligomeris a polymer and can not be observed by an electron microscope. In thepresent invention, the colloidal particles (A) have particle sizes offrom 4 to 50 nm, and the modified metal oxide particles obtained bycovering with (B2) have particle sizes of from 4.5 to 60 nm. Theincrease in the particle size corresponds to the negatively chargedcolloidal particles comprising diantimony pentaoxide and silica, anoligomer thereof or a mixture thereof (B2) which are chemically bondedto the surface of the positively charged colloidal particles (A) andthereby cover the colloidal particles (A).

The modified stannic oxide or modified stannic oxide-zirconium oxidecomposite colloidal particles, the surface of which is covered with theamine-containing Sb₂O₅ colloid (B1) of the present invention, arenegatively charged in the sol.

The above stannic oxide-zirconium oxide composite colloidal particlesare positively charged, and the Sb₂O₅ colloid is negatively charged.Accordingly, it is considered that the negatively charged Sb₂O₅ colloidis electrically attracted to the periphery of the positively chargedstannic oxide-zirconium oxide composite colloidal particles by mixing,the Sb₂O₅ colloid is bonded to the surface of the positively chargedcolloidal particles by a chemical bond, and the surface of thepositively charged particles as nuclei are covered with the negativelycharged Sb₂O₅, thereby to form modified stannic oxide-zirconium oxidecomposite colloidal particles.

However, when the stannic oxide-zirconium oxide composite colloidalparticles having particle sizes of from 4 to 50 nm as a nucleus sol andthe amine-containing Sb₂O₅ colloidal particles, an oligomer thereof or amixture thereof (B1) as a coating sol are mixed, if the amount of themetal oxide in the coating sol is smaller than 1 part by weight per 100parts by weight of the metal oxide (SnO₂ or ZrO₂+SnO₂) in the nucleussol, no stable sol can be obtained. It is considered that when theamount of the Sb₂O₅ colloid is insufficient, the surface of the stannicoxide-zirconium oxide composite colloidal particles as nuclei can not besufficiently covered with the colloidal particles, and the formedcolloidal particles are likely to agglomerate, which makes the formedsol unstable. Accordingly, the amount of the Sb₂O₅ colloidal particlesor an oligomer thereof to be mixed may be smaller than the amountrequired to cover the entire surface of the stannic oxide-zirconiumoxide composite colloidal particles, but is an amount at least theminimum amount required to form a stable sol of modified stannicoxide-zirconium oxide composite colloidal particles. If the Sb₂O₅colloidal particles or an oligomer thereof in an amount exceeding theamount to be used for the surface coating are used for the above mixing,the obtained sol is merely a stable mixed sol of an aqueous mediumcontaining the Sb₂O₅ colloidal particles, an oligomer thereof or amixture thereof, and the formed sol of modified stannic oxide-zirconiumoxide composite colloidal particles.

To modify the stannic oxide-zirconium oxide composite colloidalparticles by covering the surface, the amount of the Sb₂O₅ colloid, anoligomer thereof or a mixture thereof (B1) to be used is preferably atmost 50 parts by weight as the metal oxide in the coating sol per 100parts by weight of the metal oxide (SnO₂ or ZrO₂+SnO₂) of the nucleussol.

The modified stannic oxide or modified stannic oxide-zirconium oxidecomposite colloidal particles, the surface of which is covered with acomposite colloid comprising diantimony pentaoxide and silica, anoligomer thereof or a mixture thereof (B2) in the present invention, arenegatively charged in the sol.

The above stannic oxide-zirconium oxide composite colloidal particlesare positively charged, and the composite colloid comprising diantimonypentaoxide and silica is negatively charged. Accordingly, it isconsidered that the negatively charged composite colloid comprisingdiantimony pentaoxide and silica is electrically attracted to theperiphery of the positively charged stannic oxide-zirconium oxidecomposite colloidal particles by mixing, the composite colloidcomprising diantimony pentaoxide and silica is bonded to the surface ofthe positively charged colloidal particles by a chemical bond, and thesurface of the positively charged particles as nuclei is covered withthe negatively charged composite colloid comprising diantimonypentaoxide and silica, thereby to form modified stannic oxide-zirconiumoxide composite colloidal particles.

However, when the stannic oxide-zirconium oxide composite colloidalparticles having particle sizes of from 4 to 50 nm as a nuclei sol and acomposite colloid comprising diantimony pentaoxide and silica, anoligomer thereof or a mixture thereof (B2) as a coating sol are mixed,if the amount of the metal oxide in the coating sol is smaller than 1part by weight per 100 parts by weight of the metal oxide (SnO₂ orZrO₂+SnO₂) in the nucleus sol, no stable sol can be obtained. It isconsidered that when the amount of the composite colloid comprisingdiantimony pentaoxide and silica is insufficient, the surface of thestannic oxide-zirconium oxide composite colloidal particles as nuclei isnot sufficiently covered with the composite colloidal particles, and theformed colloidal particles are likely to agglomerate, which makes theformed sol unstable. Accordingly, the amount of the composite colloidalparticles comprising diantimony pentaoxide and silica, an oligomerthereof or a mixture thereof to be mixed may be smaller than the amountrequired to cover the entire surface of the stannic oxide-zirconiumoxide composite colloidal particles, but is an amount at least theminimum amount required to form a stable sol of modified stannicoxide-zirconium oxide composite colloidal particles. If the compositecolloidal particles comprising diantimony pentaoxide and silica, anoligomer thereof or a mixture thereof in an amount exceeding the amountto be used for the surface coating are used for the above mixing, theobtained sol is merely a stable mixed sol of an aqueous mediumcontaining the composite colloid of diantimony pentaoxide and silica, anoligomer thereof or a mixture thereof, and the formed sol of modifiedstannic oxide-zirconium oxide composite colloidal particles.

To modify the stannic oxide-zirconium oxide composite colloidalparticles by covering the surface, the amount of the composite colloidcomprising diantimony pentaoxide and silica, an oligomer thereof or amixture thereof (B2) to be used is preferably at most 50 parts by weightas the metal oxide in the coating sol per 100 parts by weight of themetal oxide (SnO₂ or ZrO₂+SnO₂) in the nucleus sol.

In the present invention, when the stannic oxide is used for nuclei, astable sol of modified stannic oxide colloidal particles can be obtainedfrom step (a1): a step of preparing a stannic oxide aqueous solcontaining stannic oxide colloidal particles having particle sizes offrom 4 to 50 nm in a concentration of SnO₂ of from 1 to 50 wt %, step(b1): a step of mixing the stannic oxide aqueous sol obtained in theabove step (a1) with an aqueous medium containing alkylamine-containingSb₂O₅ colloidal particles having a M/Sb₂O₅ molar ratio (M represents anamine molecule) of from 0.02 to 4.00, an oligomer thereof or a mixturethereof, in a weight ratio of Sb₂O₅/SnO₂ as calculated as metal oxidesof from 0.01 to 0.50, and step (c1): a step of aging the aqueous mediumobtained in step (b1) at a temperature of from 20 to 300° C. for from0.1 to 50 hours. The sol obtained in step (c1) may be further subjectedto step (d1) when the stannic oxide sol obtained in step (a1) containsanions. Namely, a stable sol of modified stannic oxide colloidalparticles can be obtained by further carrying out step (d1): a step ofbringing the modified stannic oxide aqueous sol obtained in step (c1)into contact with an anion exchanger to remove anions present in thesol, and aging the aqueous sol at a temperature of from 20 to 300° C.for from 0.1 to 50 hours. Aging at a temperature of at least 100° C. canbe carried out by using an autoclave. The sol is a sol containingmodified stannic oxide particles which comprise, as nuclei, stannicoxide colloidal particles (A) having particle sizes of from 4 to 50 nm,and as a coating covering the surface of the nuclei,alkylamine-containing Sb₂O₅ colloidal particles having a M/Sb₂O₅ molarratio (M represents an amine molecule) of from 0.02 to 4.00, an oligomerthereof or a mixture thereof (B1), in a weight ratio of (B1)/(A) of from0.01 to 0.50 based on the weights of the metal oxides, and have particlesizes of from 4.5 to 60 nm.

Further, in the present invention, when composite colloidal particlescomprising stannic oxide and zirconium oxide are used for nuclei, astable sol of modified stannic oxide-zirconium oxide composite colloidalparticles can be obtained by step (a2): a step of mixing a stannic oxideaqueous sol having particle sizes of from 4 to 50 nm and having a SnO₂concentration of from 0.5 to 50 wt %, with an aqueous solution of anoxyzirconium salt having a concentration of from 0.5 to 50 wt % ascalculated as ZrO₂, in a weight ratio of ZrO₂/SnO₂ of from 0.05 to 0.50,and heating the obtained mixed liquid at a temperature of from 60 to100° C. for from 0.1 to 50 hours to prepare a stannic oxide-zirconiumoxide composite aqueous sol, step (b2): a step of mixing the stannicoxide-zirconium oxide composite aqueous sol obtained in step (a2), withan aqueous medium containing alkylamine-containing Sb₂O₅ colloidalparticles having a M/Sb₂O₅ molar ratio (M represents an amine molecule)of from 0.02 to 4.00, an oligomer thereof or a mixture thereof, in aweight ratio of Sb₂O₅/(SnO₂/ZrO₂) of from 0.01 to 0.50 as calculated asmetal oxides, step (c2): a step of aging the aqueous medium obtained instep (b2) at a temperature of from 20 to 300° C. for from 0.1 to 50hours, and step (d2): a step of bringing the modified stannicoxide-zirconium oxide composite aqueous sol obtained in step (c2) intocontact with an anion exchanger, and aging the aqueous sol at atemperature of from 20 to 300° C. for from 0.1 to 50 hours. Aging at atemperature of at least 100° C. can be carried out by using anautoclave. The sol is a sol containing modified composite colloidalparticles comprising stannic oxide particles and zirconium oxideparticles, which comprise, as nuclei, composite colloidal particles (A)comprising stannic oxide particles and zirconium oxide particles,containing these oxides in a weight ratio of ZrO₂:SnO₂ of from 0.05:1 to0.50:1 and having particle sizes of from 4 to 50 nm, and as a coatingcovering the surface of the nuclei, alkylamine-containing Sb₂O₅colloidal particles having a M/Sb₂O₅ molar ratio (M represents an aminemolecule) of from 0.02 to 4.00, an oligomer thereof or a mixture thereof(B1), in a weight ratio of (B1)/(A) of from 0.01 to 0.50 based on theweights of the metal oxides, and have particle sizes of from 4.5 to 60nm.

The above production process may be carried out under elevated pressureby using an autoclave.

Namely, in a process of using a stannic oxide sol treated in anautoclave is used for nuclei, a modified stannic oxide aqueous sol canbe obtained from step (a3): a step of preparing a stannic oxide aqueoussol subjected to a hydrothermal treatment at a temperature of from 100to 300° C., and having particle sizes of from 4 to 50 nm and a SnO₂concentration of from 0.5 to 50 wt %, step (b3): a step of mixing thestannic oxide aqueous sol obtained in the above step (a3), with anaqueous medium containing alkylamine-containing Sb₂O₅ colloidalparticles having a M/Sb₂O₅ molar ratio (M represents an amine molecule)of from 0.02 to 4.00, an oligomer thereof or a mixture thereof, in aweight ratio of Sb₂O₅/SnO₂ as calculated as metal oxides of from 0.01 to0.50, and step (c3): a step of aging the aqueous medium obtained in step(b3) at a temperature of from 20 to 300° C. for from 0.1 to 50 hours.The sol obtained in step (c3) may be further subjected to step (d3) whenthe stannic oxide sol obtained in step (a3) contains anions. Namely, astable sol of modified stannic oxide colloidal particles can be obtainedby further carrying out step (d3): a step of bringing the modifiedstannic oxide aqueous sol obtained in step (c3) into contact with ananion exchanger to remove anions present in the sol, and aging theaqueous sol at a temperature of from 20 to 300° C. for from 0.1 to 50hours. Aging at a temperature of at least 100° C. can be carried out byusing an autoclave. This sol is a sol containing modified stannic oxideparticles which comprise, as nuclei, stannic oxide colloidal particles(A) having particle sizes of from 4 to 50 nm, and as a coating coveringthe surface of the nuclei, alkylamine-containing Sb₂O₅ colloidalparticles having a M/Sb₂O₅ molar ratio (M represents an amine molecule)of from 0.02 to 4.00, an oligomer thereof or a mixture thereof (B1), ina weight ratio of (B1)/(A) of from 0.01 to 0.50 based on the weights ofthe metal oxides, and have particle sizes of from 4.5 to 60 nm.

Further, in a process of using an aqueous sol comprising compositeparticles comprising stannic oxide sol treated in an autoclave andzirconium oxide for nuclei, a stable sol of modified stannicoxide-zirconium oxide composite colloidal particles can be obtained bystep (a4): a step of mixing a stannic oxide aqueous sol subjected to ahydrothermal treatment at a temperature of from 100 to 300° C., andhaving particle sizes of from 4 to 50 nm and a SnO₂ concentration offrom 0.5 to 50 wt %, with an aqueous solution of an oxyzirconium salthaving a concentration of from 0.5 to 50 wt % as calculated as ZrO₂, ina weight ratio of ZrO₂/SnO₂ of from 0.05 to 0.50, and heating theobtained mixed liquid at a temperature of from 60 to 100° C. for from0.1 to 50 hours to prepare a stannic oxide-zirconium oxide compositeaqueous sol having particle sizes of from 4 to 50 nm, step (b4): a stepof mixing the stannic oxide-zirconium oxide composite aqueous solobtained in step (a4), with an aqueous medium containingalkylamine-containing Sb₂O₅ colloidal particles having a M/Sb₂O₅ molarratio (M represents an amine molecule) of from 0.02 to 4.00, an oligomerthereof or a mixture thereof, in a weight ratio of Sb₂O₅/(SnO₂+ZrO₂) offrom 0.01 to 0.50 as calculated as metal oxides, step (c4): a step ofaging the aqueous medium obtained in step (b4) at a temperature of from20 to 300° C. for from 0.1 to 50 hours, and step (d4): a step ofbringing the modified stannic oxide-zirconium oxide aqueous sol obtainedin step (c4) into contact with an anion exchanger, and aging the aqueoussol at a temperature of from 20 to 300° C. for from 0.1 to 50 hours.This sol is a sol containing modified composite colloidal particlescomprising stannic oxide particles and zirconium oxide particles, whichcomprise, as nuclei, composite colloidal particles (A) comprisingstannic oxide particles and zirconium oxide particles, containing theseoxides in a weight ratio of ZrO₂:SnO₂ of from 0.05:1 to 0.50:1 andhaving particle sizes of from 4 to 50 nm, and as a coating covering thesurface of the nuclei, alkylamine-containing Sb₂O₅ colloidal particleshaving a M/Sb₂O₅ molar ratio (M represents an amine molecule) of from0.02 to 4.00, an oligomer thereof or a mixture thereof (B1), in a weightratio of (B1)/(A) of from 0.01 to 0.50 based on the weights of the metaloxides, and have particle sizes of from 4.5 to 60 nm.

In the present invention, when stannic oxide is used for nuclei, astable sol of modified stannic oxide colloidal particles can be obtainedfrom step (a5): a step of preparing a stannic oxide aqueous solcontaining stannic oxide colloidal particles having particle sizes offrom 4 to 50 nm in a SnO₂ concentration of from 1 to 50 wt %, step (b5):a step of mixing the stannic oxide aqueous sol obtained in the abovestep (a5), with an aqueous medium containing composite colloidalparticles of diantimony pentaoxide and silica having a SiO₂/Sb₂O₅ molarratio of from 0.55 to 55, an oligomer thereof or a mixture thereof, in aweight ratio of (Sb₂O₅+SiO₂)/SnO₂ as calculated as metal oxides of from0.01 to 0.50, and step (c5): a step of aging the aqueous medium obtainedin step (b5) at a temperature of from 20 to 300° C. for from 0.1 to 50hours. The sol obtained in step (c5) may be further subjected to step(d5) when the stannic oxide sol obtained in step (a5) contains anions.Namely, a stable sol of modified stannic oxide colloidal particles canbe obtained by further carrying out step (d5): a step of bringing themodified stannic oxide aqueous sol obtained in step (c5) with an anionexchanger to remove anions present in the sol, and aging the aqueous solat a temperature of from 20 to 300° C. for from 0.1 to 50 hours. Agingat a temperature of at least 100° C. can be carried out by using anautoclave. This sol is a sol containing modified stannic oxideparticles, which comprise, as nuclei, stannic oxide colloidal particles(A) having particle sizes of from 4 to 50 nm, and as a coating coveringthe surface of the nuclei, composite colloidal particles comprisingdiantimony pentaoxide and silica having a SiO₂/Sb₂O₅ molar ratio of from0.55 to 55, an oligomer thereof or a mixture thereof (B2), in a weightratio of (B2)/(A) of from 0.01 to 0.50 based on the weights of the metaloxides, and have particle sizes of from 4.5 to 60 nm.

Further, in the present invention, when composite colloidal particles ofstannic oxide and zirconium oxide are used for nuclei, a stable sol ofmodified stannic oxide-zirconium oxide composite colloidal particles canbe obtained by step (a6): a step of mixing a stannic oxide aqueous solhaving particle sizes of from 4 to 50 nm and having a SnO₂ concentrationof from 0.5 to 50 wt %, with an aqueous solution of an oxyzirconium salthaving a concentration of from 0.5 to 50 wt % as calculated as ZrO₂, ina weight ratio of ZrO₂/SnO₂ of from 0.05 to 0.50, and heating theobtained mixed liquid at a temperature of from 60 to 100° C. for from0.1 to 50 hours to prepare a stannic oxide-zirconium oxide compositeaqueous sol having particle sizes of from 4 to 50 nm, step (b6): a stepof mixing the stannic oxide-zirconium oxide aqueous composite solobtained in step (a6), with an aqueous medium containing compositecolloidal particles of diantimony pentaoxide and silica having aSiO₂/Sb₂O₅ molar ratio of from 0.55 to 55, an oligomer thereof or amixture thereof, in a weight ratio of (Sb₂O₅+SiO₂)/(SnO₂+ZrO₂) ascalculated as metal oxides of from 0.01 to 0.50, step (c6): a step ofaging the aqueous medium obtained in step (b6) at a temperature of from20 to 300° C. for from 0.1 to 50 hours, and step (d6): a step ofbringing the modified stannic oxide-zirconium oxide aqueous sol obtainedin step (c6) into contact with an anion exchanger, and aging the aqueoussol at a temperature of from 20 to 300° C. for from 0.1 to 50 hours.Aging at a temperature of at least 100° C. can be carried out by usingan autoclave. This sol is a sol containing modified composite colloidalparticles comprising stannic oxide particles and zirconium oxideparticles, which comprise, as nuclei, composite colloidal particles (A)comprising stannic oxide particles and zirconium oxide particles,containing these oxides in a weight ratio of ZrO₂:SnO₂ of from 0.05:1 to0.50:1 and having particle sizes of from 4 to 50 nm, and as a coatingcovering the surface of the nuclei, composite colloidal particlescomprising diantimony pentaoxide and silica having a SiO₂/Sb₂O₅ molarratio of from 0.55 to 55, an oligomer thereof or a mixture thereof (B2),in a weight ratio of (B2)/(A) of from 0.01 to 0.50 based on the weightsof the metal oxides, and have particle sizes of from 4.5 to 60 nm.

The above production process may be carried out under elevated pressureby using an autoclave.

Namely, in a process using a stannic oxide sol treated in an autoclavefor nuclei, a modified stannic oxide aqueous sol can be obtained fromstep (a7): a step of preparing a stannic oxide aqueous sol subjected toa hydrothermal treatment at a temperature of from 100 to 300° C., andhaving particle sizes of from 4 to 50 nm and a SnO₂ concentration offrom 0.5 to 50 wt %, step (b7): a step of mixing the stannic oxideaqueous sol obtained in the above step (a7), with an aqueous mediumcontaining composite colloidal particles of diantimony pentaoxide andsilica having a SiO₂/Sb₂O₅ molar ratio of from 0.55 to 55, an oligomerthereof or a mixture thereof, in a weight ratio of (Sb₂O₅+SiO₂)/SnO₂ ascalculated as metal oxides of from 0.01 to 0.50, and step (c7): a stepof aging the aqueous medium obtained in step (b7) at a temperature offrom 20 to 300° C. for from 0.1 to 50 hours. The sol obtained in step(c7) may be further subjected to step (d7) when the stannic oxide solobtained in step (a7) contains anions. Namely, a stable sol of modifiedstannic oxide colloidal particles can be obtained by further carryingout step (d7): a step of bringing the modified stannic oxide aqueous solobtained in step (c7) into contact with an anion exchanger to removeanions present in the sol, and aging the aqueous sol at a temperature offrom 20 to 300° C. for from 0.1 to 50 hours. This sol is a solcontaining modified stannic oxide particles, which comprise, as nuclei,stannic oxide colloidal particles (A) having particle sizes of from 4 to50 nm, and as a coating covering the surface of the nuclei, compositecolloidal particles comprising diantimony pentaoxide and silica having aSiO₂/Sb₂O₅ molar ratio of from 0.55 to 55, an oligomer thereof or amixture thereof (B2), in a weight ratio of (B2)/(A) of from 0.01 to 0.50based on the weights of the metal oxides, and have particle sizes offrom 4.5 to 60 nm.

Further, in a process of using an aqueous sol comprising compositeparticles comprising stannic oxide sol treated in an autoclave andzirconium oxide for nuclei, a stable sol of modified stannicoxide-zirconium oxide composite colloidal particles can be obtained bystep (a8): a step of mixing a stannic oxide aqueous sol subjected to ahydrothermal treatment at a temperature of from 100 to 300° C., andhaving particle sizes of from 4 to 50 nm and a SnO₂ concentration offrom 0.5 to 50 wt %, with an aqueous solution of an oxyzirconium salthaving a concentration of from 0.5 to 50 wt % as calculated as ZrO₂, ina weight ratio of ZrO₂/SnO₂ of from 0.05 to 0.50, and heating theobtained mixed liquid at a temperature of from 60 to 100° C. for from0.1 to 50 hours to prepare a stannic oxide-zirconium oxide compositeaqueous sol having particle sizes of from 4 to 50 nm, step (b8): a stepof mixing the aqueous stannic oxide-zirconium oxide composite solobtained in step (a8), with an aqueous medium containing compositecolloidal particles of diantimony pentaoxide and silica having aSiO₂/Sb₂O₅ molar ratio of from 0.55 to 55, an oligomer thereof or amixture thereof, in a weight ratio of (Sb₂O₅+SiO₂)/(SnO₂+ZrO₂) ascalculated as metal oxides of from 0.01 to 0.50, step (c8): a step ofaging the aqueous medium obtained in step (b8) at a temperature of from20 to 300° C. for from 0.1 to 50 hours, and step (d8): a step ofbringing the modified stannic oxide-zirconium oxide composite aqueoussol obtained in step (c8) into contact with an anion exchanger, andaging the aqueous sol at a temperature of from 20 to 300° C. for from0.1 to 50 hours. This sol is a sol containing modified compositecolloidal particles comprising stannic oxide particles and zirconiumoxide particles, which comprise, as nuclei, composite colloidalparticles (A) comprising stannic oxide particles and zirconium oxideparticles, containing these oxides in a weight ratio of ZrO₂:SnO₂ offrom 0.05:1 to 0.50:1 and having particle sizes of from 4 to 50 nm, andas a coating covering the surface of the nuclei, composite colloidalparticles comprising diantimony pentaoxide and silica having aSiO₂/Sb₂O₅ molar ratio of from 0.55 to 55, an oligomer thereof or amixture thereof (B2), in a weight ratio of (B2)/(A) of from 0.01 to 0.50based on the weights of the metal oxides, and have particle sizes offrom 4.5 to 60 nm.

The process for producing the sol of the present invention is classifiedinto two cases, i.e. a case where particles used for nuclei are stannicoxide, and a case where the particles are a composite sol comprisingstannic oxide and zirconium oxide. The sol in the former case has arutile crystal structure, and one obtained by coating such a sol as acoating composition on a substrate and baking it has a high refractiveindex (refractive index of from 1.7 to 1.8 as calculated from a coatingfilm) and excellent transparency. Further, the sol in the latter caseprovides, in addition to the performance of the former sol, excellentweather (light) resistance by employing zirconium oxide in combination.

Each of the above sols can be classified into a case where stannic oxideis not treated in an autoclave and a case where it is treated in anautoclave. The sol in the latter case provides excellent performance ofthe former, and further, a coating film obtained by coating each sol asa coating composition on a substrate and baking it has a high refractiveindex (refractive index of from 1.8 to 1.9 as calculated from thecoating film).

The above modified stannic oxide-zirconium oxide composite colloidalparticles can be observed by an electron microscope, and have particlesizes of from about 4.5 to about 60 nm. The sol obtained by the abovemixing has a pH of from about 1 to about 9, and contains anions such asCl⁻, NO₃ ⁻ or CH₃COO⁻ derived from oxyzirconium salts used formodification in a large amount, and thus the colloidal particles haveundergone microagglomeration, and the sol has low transparency.

By removing, in step (d), anions in the sol obtained by the abovemixing, a stable sol of modified stannic oxide-zirconium oxide compositecolloidal particles having a pH of from 3 to 11.5 and having favorabletransparency can be obtained.

Removal of anions in step (d) may be carried out by treating the solobtained by the above mixing with a hydroxyl group form anion exchangeresin at a temperature of at most 100° C., preferably from roomtemperature (20° C.) to 60° C. The hydroxyl group form anion exchangeresin may be commercially available, and preferred is a strongly acidicform such as Amberlite 410.

The treatment with a hydroxyl group form anion exchange resin in step(d) is carried out particularly preferably at a concentration of all themetal oxides of the sol obtained by mixing in step (c) of from 1 to 10wt %.

In the production processes (a1 to d1), (a2 to d2), (a5 to d5) and (d6to d6) employing a stannic oxide sol not subjected to a hydrothermaltreatment (autoclave treatment) as a material, aging at a temperature offrom 20 to 100° C. for from 0.1 to 200 hours may be carried out in step(c), or alternatively, it is possible to carry out a hydrothermaltreatment at a temperature of from 100 to 300° C. for from 0.1 to 200hours.

Further, in the production processes (a3 to d3), (a4 to d4), (a7 to d7)and (a8 to d8) employing a stannic oxide sol subjected to a hydrothermaltreatment (autoclave treatment) as a material, aging at a temperature offrom 20 to 100° C. for from 0.1 to 200 hours may be carried out in step(c), or alternatively, it is possible to carry out a hydrothermaltreatment at a temperature of from 100 to 300° C. for from 0.1 to 200hours.

The modified stannic oxide aqueous sol and the modified stannicoxide-zirconium oxide aqueous composite sol of the present inventionpreferably have a pH of from 1.5 to 11.5. If the pH exceeds 11.5, theSb₂O₅ colloidal particles which cover the modified stannic oxidecolloidal particles or the modified stannic oxide-zirconium oxidecomposite colloidal particles are likely to be dissolved in the liquid.Further, if the total concentration of all the metal oxides in the solof the modified stannic oxide colloidal particles or the modifiedstannic oxide-zirconium oxide composite colloidal particles exceeds 60wt %, such a sol tends to be unstable. The concentration preferred foran industrial product is at a level of from 10 to 50 wt %.

The modified metal oxide sol of the present invention may contain otheroptional components so long as the object of the present invention canbe achieved. Particularly when an oxycarboxylic acid is contained in anamount of at most about 30 wt % to the total amount of all the metaloxides, a colloid having further improved performance such asdispersibility will be obtained.

When the modified metal oxide sol of the present invention is mixed witha silane coupling agent or a hydrolysate thereof to form a coatingcomposition, a silane coupling agent or a hydrolysate thereof has a pHexhibiting weak acidity, and thus an oxycarboxylic acid may be added tothe modified metal oxide sol of the present invention to preliminarilylower the pH. In such a case, the modified metal oxide sol has a pH offrom about 4 to about 6. Accordingly, the compatibility between themodified metal oxide particles and the silane coupling component in thecoating composition will improve, whereby coating characteristics andthe storage stability of the coating composition will improve.

The oxycarboxylic acid to be used may, for example, be lactic acid,tartaric acid, citric acid, gluconic acid, malic acid or glycolic acid.Further, an alkali component may be contained, such as an alkali metalhydroxide of e.g. Li, Na, K, Rb or Cs, NH₄, an alkylamine such asethylamine, triethylamine, isopropylamine or n-propylamine; anaralkylamine such as benzylamine; an alicyclic amine such as piperidine;or an alkanolamine such as monoethanolamine or triethanolamine. They maybe used in combination as a mixture of two or more of them. Further,they may be used together with the above acid component in combination.They may be contained in an amount of at most about 30 wt % based on thetotal amount of all the metal oxides.

In order to further increase the sol concentration, the sol may beconcentrated up to a level of 50 wt % by a conventional method such asan evaporation method or an ultrafiltration method. Further, in order toadjust the pH of the sol, the above alkali metal, organic base (amine),oxycarboxylic acid or the like may be added to the sol after theconcentration. Particularly, a sol having a total concentration of themetal oxides of from 10 to 40 wt % is practically preferred. When anultrafiltration method is employed as a concentration method,polyanions, ultrafine particles, etc. which coexist in the sol passthrough an ultrafilter membrane together with water, whereby suchpolyanions, ultrafine particles, etc. which cause the sol to beunstable, can be removed from the sol.

When the modified metal oxide colloid obtained by the above mixing is anaqueous sol, an organosol can be obtained by replacing the aqueousmedium in the aqueous sol with a hydrophilic organic solvent. Thisreplacement can be obtained by a conventional method such as anevaporation method or an ultrafiltration method. The hydrophilic organicsolvent may, for example, be a lower alcohol such as methyl alcohol,ethyl alcohol or isopropyl alcohol; a linear amide such asdimethylformamide or N,N′-dimethylacetamide; a cyclic amide such asN-methyl-2-pyrrolidone; or a glycol such as ethyl cellosolve or ethyleneglycol.

The formula (I) for component (S) to be used for the coating compositionof the present invention:(R¹)_(a)(R³)_(b)Si(OR²)_(4−(a+b))  (I)includes an organic silicon compound wherein R¹ and R³ are the sameorganic groups or different organic groups, and a and b are the sameintegers or different integers. The organic silicon compound of theformula (I) for component (A) may, for example, be tetramethoxysilane,tetraethoxysilane, tetra n-propoxysilane, tetraisopropoxysilane, tetran-butoxysilane, tetraacetoxysilane, methyltrimethoxysilane,methyltripropoxysilane, methyltriacetoxysilane, methyltributoxysilane,methyltripropoxysilane, methyltriamyloxysilane, methyltriphenoxysilane,methyltribenzyloxysilane, methyltriphenetyloxysilane,glycidoxymethyltrimethoxysilane, glycidoxymethyltriethoxysilane,α-glycidoxyethyltrimethoxysilane, α-glycidoxyethyltriethoxysilane,β-glycidoxyethyltrimethoxysilane, β-glycidoxyethyltriethoxysilane,α-glycidoxypropyltrimethoxysilane, α-glycidoxypropyltriethoxysilane,β-glycidoxypropyltrimethoxysilane, β-glycidoxypropyltriethoxysilane,γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane,γ-glycidoxypropyltripropoxysilane, γ-glycidoxypropyltributoxysilane,γ-glycidoxypropyltriphenoxysilane, α-glycidoxybutyltrimethoxysilane,α-glycidoxybutyltriethoxysilane, β-glycidoxybutyltriethoxysilane,γ-glycidoxybutyltrimethoxysilane, γ-glycidoxybutyltriethoxysilane,δ-glycidoxybutyltrimethoxysilane, δ-glycidoxybutyltriethoxysilane,(3,4-epoxycyclohexyl)methyltrimethoxysilane,(3,4-epoxycyclohexyl)methyltriethoxysilane,β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane,β-(3,4-epoxycyclohexyl)ethyltriethoxysilane,β-(3,4-epoxycyclohexyl)ethyltripropoxysilane,β-(3,4-epoxycyclohexyl)ethyltributoxysilane,β-(3,4-epoxycyclohexyl)ethyltriphenoxysilane,γ-(3,4-epoxycyclohexyl)propyltrimethoxysilane,γ-(3,4-epoxycyclohexyl)propyltriethoxysilane,δ-(3,4-epoxycyclohexyl)butyltrimethoxysilane,δ-(3,4-epoxycyclohexyl)butyltriethoxysilane,glycidoxymethylmethyldimethoxysilane,glycidoxymethylmethyldiethoxysilane,α-glycidoxyethylmethyldimethoxysilane,α-glycidoxyethylmethyldiethoxysilane,β-glycidoxyethylmethyldimethoxysilane,β-glycidoxyethylethyldimethoxysilane,α-glycidoxypropylmethyldimethoxysilane,α-glycidoxypropylmethyldiethoxysilane,β-glycidoxypropylmethyldimethoxysilane,β-glycidoxypropylethyldimethoxysilane,γ-glycidoxypropylmethyldimethoxysilane,γ-glycidoxypropylmethyldiethoxysilane,γ-glycidoxypropylmethyldipropoxysilane,γ-glycidoxypropylmethyldibutoxysilane,γ-glycidoxypropylmethyldiphenoxysilane,γ-glycidoxypropylethyldimethoxysilane,γ-glycidoxypropylethyldiethoxysilane,γ-glycidoxypropylvinyldimethoxysilane,γ-glycidoxypropylvinyldiethoxysilane, ethyltrimethoxysilane,ethyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane,vinyltriacetoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane,phenyltriacetoxysilane, γ-chloropropyltrimethoxysilane,γ-chloropropyltriethoxysilane, γ-chloropropyltriacetoxysilane,3,3,3-trifluoropropyltrimethoxysilane,γ-methacryloxypropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane,γ-mercaptopropyltriethoxysilane, β-cyanoethyltriethoxysilane,chloromethyltrimethoxysilane, chloromethyltriethoxysilane,N-(β-aminoethyl) γ-aminopropyltrimethoxysilane, N-(β-aminoethyl)γ-aminopropylmethyldimethoxysilane, γ-aminopropylmethyldimethoxysilane,N-(β-aminoethyl) γ-aminopropyltriethoxysilane, N-(β-aminoethyl)γ-aminopropylmethyldiethoxysilane, dimethyldimethoxysilane,phenylmethyldimethoxysilane, dimethyldiethoxysilane,phenylmethyldiethoxysilane, γ-chloropropylmethyldimethoxysilane,γ-chloropropylmethyldiethoxysilane, dimethyldiacetoxysilane,γ-methacryloxypropylmethyldimethoxysilane,γ-methacryloxypropylmethyldiethoxysilane,γ-mercaptopropylmethyldimethoxysilane, γ-mercaptomethyldiethoxysilane,methylvinyldimethoxysilane, or methylvinyldiethoxysilane. These organicsilicon compounds may be used alone or in combination as a mixture oftwo or more of them.

The hydrolysates of organic silicon compounds of the formula (I) forcomponent (S) to be used for the coating composition of the presentinvention, are compounds obtained by hydrolysis of the organic siliconcompounds of the formula (I) so that a part or all of R² are substitutedby hydrogen atoms. Such hydrolysates of the organic silicon compounds ofthe formula (I) may be used alone or in combination as a mixture of twoor more of them. The hydrolysis is carried out by adding an aqueousacidic solution such as an aqueous hydrochloric acid solution, anaqueous sulfuric acid solution or an aqueous acetic acid solution to theorganic silicon compound, followed by stirring.

The organic silicon compound of the formula (II):[(R⁴)_(c)Si(OX)_(3−c)]₂Y  (II)for component (S) to be used for the coating composition of the presentinvention, may, for example, be methylenebismethyldimethoxysilane,ethylenebisethyldimethoxysilane, propylenebisethyldiethoxysilane orbutylenebismethyldiethoxysilane. These organic silicon compounds may beused alone or in combination as a mixture of two or more of them.

The hydrolysates of organic silicon compounds of the formula (II) forcomponent (S) to be used for the coating composition of the presentinvention, are compounds obtained by hydrolysis of the organic siliconcompounds of the formula (II) so that a part or all of X are substitutedby hydrogen atoms. Such hydrolysates of the organic silicon compounds ofthe formula (II) may be used alone or in combination as a mixture of twoor more of them. The hydrolysis is carried out by adding an aqueousacidic solution such as an aqueous hydrochloric acid solution, anaqueous sulfuric acid solution or an aqueous acetic acid solution to theorganic silicon compound, followed by stirring.

Component (S) to be used for the coating composition of the presentinvention, is at least one silicon-containing substance selected fromthe group consisting of organic silicon compounds of the formulae (I)and (II) and their hydrolysates.

Component (S) to be used for the coating composition of the presentinvention, is preferably at least one silicon-containing substanceselected from the group consisting of organic silicon compounds of theformula (I) and their hydrolysates. Particularly preferred are organicsilicon compounds of the formula (I) wherein either one of R¹ and R³ isan organic group having an epoxy group, R² is an alkyl group, and eachof a and b is 0 or 1, provided that a+b is 1 or 2, and theirhydrolysates. Examples of such preferred organic silicon compoundsinclude glycidoxymethyltrimethoxysilane, glycidoxymethyltriethoxysilane,α-glycidoxyethyltrimethoxysilane, α-glycidoxyethyltriethoxysilane,β-glycidoxyethyltrimethoxysilane, β-glycidoxyethyltriethoxysilane,α-glycidoxypropyltrimethoxysilane, α-glycidoxypropyltriethoxysilane,β-glycidoxypropyltrimethoxysilane, β-glycidoxypropyltriethoxysilane,γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane,γ-glycidoxypropyltripropoxysilane, γ-glycidoxypropyltributoxysilane,γ-glycidoxypropyltriphenoxysilane, α-glycidoxybutyltrimethoxysilane,α-glycidoxybutyltriethoxysilane, β-glycidoxybutyltriethoxysilane,γ-glycidoxybutyltrimethoxysilane, γ-glycidoxybutyltriethoxysilane,δ-glycidoxybutyltrimethoxysilane, δ-glycidoxybutyltriethoxysilane,glycidoxymethylmethyldimethoxysilane,glycidoxymethylmethyldiethoxysilane,α-glycidoxyethylmethyldimethoxysilane,α-glycidoxyethylmethyldiethoxysilane,β-glycidoxyethylmethyldimethoxysilane,β-glycidoxyethylethyldimethoxysilane,α-glycidoxypropylmethyldimethoxysilane,α-glycidoxypropylmethyldiethoxysilane,β-glycidoxypropylmethyldimethoxysilane,β-glycidoxypropylethyldimethoxysilane,γ-glycidoxypropylmethyldimethoxysilane,γ-glycidoxypropylmethyldiethoxysilane,γ-glycidoxypropylmethyldipropoxysilane,γ-glycidoxypropylmethyldibutoxysilane,γ-glycidoxypropylmethyldiphenoxysilane,γ-glycidoxypropylethyldimethoxysilane,γ-glycidoxypropylethyldiethoxysilane,γ-glycidoxypropylvinyldimethoxysilane, andγ-glycidoxypropylvinyldiethoxysilane.

More preferred are γ-glycidoxypropyltrimethoxysilane,γ-glycidoxypropylmethyldiethoxysilane,γ-glycidoxypropylmethyldimethoxysilane and their hydrolysates, and theymay be used alone or in combination as a mixture. Further,γ-glycidoxypropyltrimethoxysilane,γ-glycidoxypropylmethyldiethoxysilane,γ-glycidoxypropylmethyldimethoxysilane or a hydrolysate thereof may beused in combination with a tetrafunctional compound of the formula (I)wherein a+b=0. Examples of the tetrafunctional compound includetetramethoxysilane, tetraethoxysilane, tetraisopropoxysilane, tetran-propoxysilane, tetra n-butoxysilane, tetra tert-butoxysilane and tetrasec-butoxysilane.

The modified metal oxide particles to be used for component (T1) andcomponent (T2) in the coating composition of the present invention maybe any one of the modified sols as defined in the above 1 to 6.

The coating composition of the present invention is obtained by blendingcomponent (T1) or (T2) in a proportion of preferably from 1 to 500 partsby weight, particularly preferably from 50 to 250 parts by weight, with100 parts by weight of component (S). Namely, the coating compositionpreferably contains 100 parts by weight of component (S): an organicsilicon compound and from 1 to 500 parts by weight of component (T1):modified metal oxide particles, which comprise, as nuclei, colloidalparticles (A) being stannic oxide particles or composite particlescomprising stannic oxide particles and zirconium oxide particles,containing these oxides in a weight ratio of ZrO₂:SnO₂ of from 0:1 to0.50:1 and having particle sizes of from 4 to 50 nm, and as a coatingcovering the surface of the nuclei, alkylamine-containing Sb₂O₅colloidal particles having a M/Sb₂O₅ molar ratio (M represents an aminemolecule) of from 0.02 to 4.00, an oligomer thereof or a mixture thereof(B1), in a weight ratio of (B1)/(A) of from 0.01 to 0.50 based on theweights of the metal oxides, and have particle sizes of from 4.5 to 60nm. If the amount of the modified metal oxide sol is less than 1 part byweight, a cured film to be obtained will have a low refractive index,and its application to a substrate will be remarkably limited. Further,if it exceeds 500 parts by weight, cracks or the like are likely tooccur between the cured film and the substrate, and there is highpossibility that the transparency decreases.

The coating composition of the present invention is obtained by blendingcomponent (T1) or (T2) in a proportion of preferably from 1 to 500 partsby weight, particularly preferably from 50 to 250 parts by weight, with100 parts by weight of component (S). Namely, the coating compositionpreferably contains 100 parts by weight of component (S): an organicsilicon compound and from 1 to 500 parts by weight of component (T2):modified metal oxide particles, which comprise, as nuclei, colloidalparticles (A) being stannic oxide particles or composite particlescomprising stannic oxide particles and zirconium oxide particles,containing these oxides in a weight ratio of ZrO₂:SnO₂ of from 0:1 to0.50:1 and having particle sizes of from 4 to 50 nm, and as a coatingcovering the surface of the nuclei, composite colloidal particlescomprising diantimony pentaoxide and silica having a SiO₂/Sb₂O₅ molarratio of from 0.55 to 55, an oligomer thereof or a mixture thereof (B2),in a weight ratio of (B2)/(A) of from 0.01 to 0.50 based on the weightsof the metal oxides, and have particle sizes of from 4.5 to 60 nm. Ifthe amount of the modified metal oxide sol is less than 1 part byweight, a cured film to be obtained will have a low refractive index,and its application to a substrate will be remarkably limited. Further,if it exceeds 500 parts by weight, cracks or the like are likely tooccur between the cured film and the substrate, and there is highpossibility that the transparency decreases.

To the coating composition of the present invention, a curing agent maybe incorporated so as to accelerate the reaction, fine particulate of ametal oxide may be incorporated so as to adjust the refractive indexwith lenses to be various substrates, or a surface active agent may beincorporated so as to improve wettability at the time of coating and toimprove smoothness of the cured film. Further, e.g. an ultravioletabsorber or an antioxidant may be added within a range of not impairingphysical properties of the cured film.

The curing agent may, for example, be an amine such as allylamine orethylamine, a salt or a metal salt having an acid or a base including aLewis acid or a Lewis base, such as organic carboxylic acid, chromicacid, hypochlorous acid, boric acid, perchloric acid, bromic acid,selenious acid, thiosulfuric acid, orthosilicic acid, thiocyanic acid,nitrous acid, aluminic acid or carbonic acid, or an alkoxide or chelateof a metal such as aluminum, zirconium or titanium.

Further, the fine particulate metal oxide may, for example, be fineparticles of e.g. aluminum oxide, titanium oxide, antimony oxide,zirconium oxide, silicon oxide or cerium oxide.

The coating composition of the present invention may be coated on asubstrate and cured to obtain a cured film. Curing of the coatingcomposition is carried out by hot air drying or irradiation with activeenergy rays. As the curing conditions, curing is preferably carried outin a hot air of from 70 to 200° C., particularly preferably from 90 to150° C. As the active energy rays, far infrared rays may be used,whereby damage due to heat can be suppressed to a low level.

The coating composition of the present invention may be coated on asubstrate and cured to obtain a cured film. Further, in the presentinvention, an optical element which has a laminate film comprising acured film made of the above coating composition, a shock absorbing filmand an antireflection film on its surface, can be obtained.

As a method of forming the cured film made of the coating composition ofthe present invention on a substrate, the above method of coating thecoating composition on a substrate, may be mentioned. As a coatingmeans, a conventional method such as a dipping method, a spin coatingmethod or a spray coating method may be employed. However, a dippingmethod or a spin coating method is particularly preferred from theviewpoint of the area degree.

Further, adhesion between the substrate and the cured film may beimproved by applying chemical treatment by means of an acid, an alkalior various organic solvents, physical treatment by means of plasma orultraviolet rays, washing treatment by means of various washing agentsor primer treatment by means of various resins, prior to coating theabove coating composition on the substrate.

It is also possible to add the modified metal oxide particles disclosedas component (T1) or (T2) as a refractive index adjusting agent to theabove various resins for primer.

Further, an antireflection film of vapor deposition film of an inorganicoxide to be formed on the cured film made of the coating composition ofthe present invention is not particularly limited, and a conventionallyknown single-layer or multilayer antireflection film of a vapordeposition film of an inorganic oxide may be used. Examples of theantireflection film include antireflection films as disclosed inJP-A-2-262104 and JP-A-56-116003.

The shock absorbing film will improve a shock resistance. The shockabsorbing film is made of a polyacrylic acid resin, polyvinyl acetateresin, or polyvinyl alcohol resin, etc.

Further, the cured film made of the coating composition of the presentinvention is useful as an antireflection film as a high refractive indexfilm. Further, by incorporating a functional component for e.g.antifogging, photochromic or stain proofing, it may also be used as amultifunctional film.

The optical element having the cured film made of the coatingcomposition of the present invention is useful as not only lenses foreyeglasses, but also lenses for cameras, window glasses for automobilesand optical filters for liquid crystal display or plasma displaydevices.

EXAMPLES

Preparation of Nucleus Sol

A-1-1 Preparation of Stannic Oxide Sol

41 kg of 35% hydrochloric acid and 110 kg of pure water were put in a0.5 m³ reactor lined with glass (a reactor the inner surface of whichwas covered with glass) and heated to 70° C. with stirring, and thenwith cooling, 185 kg of a 35% hydrogen peroxide solution and 90 kg of ametal tin powder (manufactured by YAMAISHI METALS CO., LTD., AT-Sn No.200N, containing 99.7% as SnO₂) were alternately added dividedly 18times in total. Addition of the hydrogen peroxide solution and the metaltin was carried out as follows. Firstly, 10 kg of the 35% hydrogenperoxide solution was gradually added and then 5 kg of the metal tin wasgradually added, and after the completion of the reaction (10 to 15minutes), addition of the hydrogen peroxide and the metal tin wasrepeated. Since the reaction was an exothermic reaction, the temperatureincreased to from 90 to 95° C. by addition of the metal tin.Accordingly, the reaction temperature was from 70 to 95° C. The ratio ofthe hydrogen peroxide to the metal tin was 2.5 as the H₂O₂/Sn molarratio. The time required for addition of the hydrogen peroxide solutionand the metal tin was 4.5 hours. After the completion of the reaction,aging was carried out by keeping the liquid temperature to from 90 to95° C. for 0.5 hour. The Sn/Cl equivalent ratio at the time of reactionwas 1.92.

After the completion of the aging, stirring was stopped, and thereaction product was cooled and left to stand overnight, whereby tinoxide colloidal aggregate settled down, and the reaction liquid wasseparated into two layers i.e. a supernatant layer and a sediment layer.The supernatant fluid was transparent and exhibited substantially nocolloidal color. The supernatant fluid was removed by a gradient method.The weight of the supernatant fluid was 205 kg. 125 kg of water wasadded to the remaining tin oxide colloidal aggregate slurry, followed bystirring at 30° C. for 4 hours, whereby the tin oxide colloidalaggregate was peptized to form a tin oxide sol.

The weight of the obtained tin oxide sol was 340 kg. The sol was a paleyellow transparent sol. The particle sizes of the tin oxide colloid wereat most 10 nm as observed by an electron microscope. It was stable evenafter left to stand at room temperature for at least 1 year.

322 kg of the pale yellow stannic oxide sol was dispersed in 2,118 kg ofwater, and 2.42 kg of isopropylamine was added thereto, followed byaging by heating at a temperature of from 80 to 85° C. for 3 hours.After cooling, the liquid was applied to a column packed with a hydroxylgroup form anion exchange resin to obtain 2,175 kg of an alkalinestannic oxide aqueous sol. The sol was stable, had very hightransparency although exhibited a colloidal color, and had a specificgravity of 1.032, a pH of 10.01, a SnO₂ content of 4.14 wt %, and anisopropylamine content of 0.11 wt %.

A-1-2 Preparation of Stannic Oxide Sol

37.5 kg of oxalic acid ((COOH)₂.2H₂O) was dissolved in 220 kg of purewater, and the solution was put in a 0.5 m³ reactor lined with glass (areactor the inner surface of which was covered with glass) and heated to70° C. with stirring, and then 150 kg of a 35% hydrogen peroxidesolution and 75 kg of a metal tin powder (manufactured by YAMAISHIMETALS CO., LTD., AT-Sn No. 200N, containing 99.7% as SnO₂) were addedthereto. The hydrogen peroxide solution and the metal tin werealternately added dividedly in 15 times. Firstly, 10 kg of the 35%hydrogen peroxide solution was added, and then 5 kg of the metal tin wasadded. After the completion of the reaction (10 to 15 minutes), theabove operation was repeated.

The time required for addition was 2.5 hours, and after completion ofthe addition, the liquid was heated for 1 hour while keeping the liquidtemperature at 90° C., and the reaction was completed. The ratio of thehydrogen peroxide to the metal tin was 2.44 as the H₂O₂/Sn molar ratio.The yield of the obtained tin oxide sol was 352 kg, and the sol had aspecific gravity of 1.22, a pH of 1.49, a SnO₂ concentration of 26.1 wt%, an oxalic acid concentration based on the charged amount of 7.6 wt %,and a (COOH)₂/SnO₂ molar ratio of 0.47. The obtained sol had thixotropicproperties but had lower thixotropic properties than those when ahydrochloric acid aqueous solution was used.

The tin oxide colloidal particles had particle sizes of from 10 to 15 nmas observed by an electron microscope, and were spherical particles withfavorable dispersibility. The sol tends to thicken when left to stand,however, the sol did not gelate and was stable after left to stand atroom temperature for 6 months.

230 kg of this pale yellow stannic oxide sol was dispersed in 1,100 kgof water, 3.0 kg of isopropylamine was added thereto, and the resultingliquid was passed through a column packed with a hydroxyl group formanion exchange resin to make the liquid alkaline, and then the sol wasaged by heating at 90° C. and then passed through a column packed withan anion exchange resin again to obtain 1,431 kg of an alkaline stannicoxide aqueous sol. The obtained sol was a stable stannic oxide solhaving a very high transparency, and having a specific gravity of 1.034,a pH of 11.33, a SnO₂ content of 4.04 wt % and an isopropylamine contentof 0.21 wt %.

A-1-3 Preparation of Stannic Oxide Sol by Treatment in an Autoclave

2,300 g of the alkaline stannic oxide aqueous sol obtained in A-1-1 wasaged by heating in an autoclave at 140° C. for 5 hours.

A-1-4 Preparation of Stannic Oxide Sol by Treatment in an Autoclave

800 kg of the alkaline stannic oxide sol obtained in A-1-2 was aged byheating in an autoclave at 140° C. for 5 hours.

A-1-5 Preparation of Stannic Oxide Sol by Treatment in an Autoclave

600 kg of the alkaline stannic oxide sol obtained in A-1-2 was aged byheating in an autoclave at 240° C. for 5 hours.

B. Preparation of Coating Materials

B-1-1 Preparation of Alkali Component-Containing Diantimony PentoxideColloid

Into a 500 ml four-necked flask, 52.6 g of diantimony trioxide(manufactured by Kanton Mikuni, containing 99.5% as Sb₂O₃), 444 g ofpure water and 40.2 g of diisopropylamine were added and heated to 70°C. with stirring with a stirrer, and 53 g of a 35% hydrogen peroxidesolution was gradually added thereto. After the completion of thereaction, the reaction mixture was subjected to filtration with a glassfilter paper (GA-100, manufactured by ADVANTEC). The obtained aqueousmedium containing alkali component-containing diantimony pentaoxidecolloid and an oligomer thereof, had a Sb₂O₅ concentration of 9.8 wt %,a diisopropylamine concentration of 6.8 wt %, and a molar ratio ofdiisopropylamine/Sb₂O₅ of 2.2, and particles of at most 10 nm wereobserved by a transmission electron microscope.

B-1-2 Preparation of Alkali Component-Containing Diantimony PentoxideColloid

Into a 100 ml vessel, 12.5 kg of diantimony trioxide (manufactured byKanton Mikuni, containing 99.5% as Sb₂O₃), 66.0 kg of pure water and12.5 kg of potassium hydroxide (containing 95% as KOH) were added, and8.4 kg of a 35% hydrogen peroxide solution was gradually added theretowith stirring. The obtained potassium antimonate aqueous solution had aSb₂O₅ concentration of 15.25 wt %, a potassium hydroxide concentrationof 5.36 wt %, and a molar ratio of K₂O/Sb₂O₅ of 1.0.

The obtained potassium antimonate aqueous solution was diluted to 2.5 wt%, and passed through a column packed with a hydrogen form cationexchange resin. To the solution of antimonic acid after the ionexchange, 6.6 kg of diisopropylamine was added with stirring, to obtainan aqueous medium containing alkali component-containing diantimonypentoxide colloid and an oligomer thereof. The aqueous medium had aSb₂O₅ concentration of 1.8 wt %, a diisopropylamine concentration of 1.2wt %, a molar ratio of diisopropylamine/Sb₂O₅ of 1.69, and particles ofat most 10 nm were observed by a transmission electron microscope.

B-2-1 Preparation of Diantimony Pentaoxide-Silica Composite Colloid

546 g of a potassium silicate aqueous solution (containing 15.4 wt % asSiO₂) was diluted with 542 g of pure water, and a potassium antimonateaqueous solution (containing 14.6 wt % as Sb₂O₅) was mixed therewithwith stirring and stirring, was continued for 1 hour to obtain a mixedaqueous solution of potassium silicate and potassium antimonate.

The obtained mixed aqueous solution of potassium silicate and potassiumantimonate was diluted with pure water to a concentration of 5 wt %, andthen the diluted solution was passed through a column packed with acation exchange resin to obtain an aqueous medium containing adiantimony pentaoxide-silica composite colloid and an oligomer thereof.

The obtained composite colloid was colorless and transparent and had apH of 1.8, and particles of at most 5 nm were observed by a transmissionelectron microscope.

Example 1 For Preparation of Modified Metal Oxide Sol

Step (a): An alkaline stannic oxide aqueous sol (A-1-1) having particlesizes of at most 10 nm and an SnO₂ concentration of 4.14 wt % wasobtained.

Step (b): 51.0 g of the aqueous medium containing an aminecomponent-containing diantimony pentaoxide colloid and an oligomerthereof prepared in B-1-1 was added to 1,207.7 g (containing 50 g asSnO₂) of the aqueous sol obtained in A-1-1 with stirring, and they weremixed in a weight ratio of (B-1-1)/(A-1-1) as calculated as metal oxidesof 0.1.

Step (c): The aqueous medium obtained in Step (b) was aged by heating at90° C. for 3 hours.

The obtained modified stannic oxide aqueous sol (diluted liquid) wasconcentrated by a filtration apparatus with an ultrafilter membrane witha molecular weight cutoff of 50,000 at room temperature to obtain 270 gof a high concentration modified stannic oxide aqueous sol. This sol hada specific gravity of 1.220, a pH of 7.90, a viscosity of 2.3 c.p. and aconcentration of 20.3 wt % as calculated as metal oxides, and wasstable.

While 9 liters of methanol was gradually added to 246 g of the abovehigh concentration modified stannic oxide aqueous sol, water wasdistilled off by a rotary evaporator under reduced pressure at a liquidtemperature of at most 30° C., to obtain 159 g of a modified stannicoxide methanol sol having water in the aqueous sol replaced withmethanol. This sol had a specific gravity of 1.092, a pH of 7.70(mixture with water in an equal weight), a viscosity of 2.3 c.p., aconcentration of 30.5 wt % as calculated as metal oxides, a watercontent of 0.65 wt %, and particle sizes of from 5 to 15 nm as observedby an electron microscope. This sol showed a colloidal color and had ahigh transparency, and it was free from e.g. precipitates, whiteturbidity and thickening and was stable even after left to stand at roomtemperature for 3 months. Further, the dry product of this sol had arefractive index of 1.76.

Example 2 For Preparation of Modified Metal Oxide Sol

The same operation as in Preparation Example 1 was carried out exceptthat 51 g of the aqueous medium containing an alkalicomponent-containing diantimony pentaoxide colloid and an oligomerthereof as the component B-1-1 in Preparation Example 1 was changed to277.8 g of the aqueous medium containing an alkali component-containingdiantimony pentaoxide colloid and an oligomer thereof as the componentB-1-2 so that the weight ratio of (B)/(A) as calculated as metal oxideswould be 0.1.

The obtained high concentration modified stannic oxide aqueous sol had aspecific gravity of 1.218, a pH of 8.80, a viscosity of 2.8 c.p. and aconcentration of 20.4 wt % as calculated as metal oxides, and wasstable.

While 10 liters of methanol was gradually added to 245 g of the abovehigh concentration modified stannic oxide aqueous sol, water wasdistilled off by a rotary evaporator under reduced pressure at a liquidtemperature of at most 30° C. to obtain 162 g of a modified stannicoxide methanol sol having water in the aqueous sol replaced withmethanol. This sol had a specific gravity of 1.093, a pH of 8.34(mixture with water in an equal weight), a viscosity of 1.8 c.p., aconcentration of 30.5 wt % as calculated as metal oxides, a watercontent of 0.81 wt % and particle sizes of from 5 to 15 nm as observedby an electron microscope. This sol showed a colloidal color and had ahigh transparency, and it was free from e.g. precipitates, whileturbidity and thickening and was stable, even after left to stand atroom temperature for 3 months. Further, the dried product of this solhad a refractive index of 1.76.

Example 3 For Preparation of Modified Metal Oxide Sol

The same operation as in Preparation Example 1 was carried out exceptthat the stannic oxide colloid as the component A-1-1 in PreparationExample 1 was changed to 1,207.7 g of the stannic oxide colloid as thecomponent A-1-3, and the aqueous medium containing an alkalicomponent-containing diantimony pentaoxide colloid and an oligomerthereof as the component B-1-1 was changed to 277.8 g of the aqueousmedium containing an alkali component-containing antimony pentaoxidecolloid and an oligomer thereof as the component B-1-2 so that theweight ratio of (B)/(A) as calculated as metal oxides would be 0.1.

The obtained high concentration modified stannic oxide aqueous sol had aspecific gravity of 1.220, a pH of 8.51, a viscosity of 2.4 c.p. and aconcentration of 21.2 wt % as calculated as metal oxides, and wasstable.

While 8 liters of methanol was gradually added to 236 g of the abovehigh concentration modified stannic oxide aqueous sol, water wasdistilled off by a rotary evaporator under reduced pressure at a liquidtemperature of at most 30° C. to obtain 160 g of a modified stannicoxide methanol sol having water in the aqueous sol replaced withmethanol. This sol had a specific gravity of 1.092, a pH of 8.0 (mixturewith water in an equal weight), a viscosity of 1.2 c.p., a concentrationof 30.5 wt % as calculated as metal oxides, a water content of 0.75 wt %and particle sizes of from 5 to 15 nm as observed by an electronmicroscope. This sol showed a colloidal color and had a hightransparency, and it was free from e.g. precipitates, white turbidityand thickening and was stable, even after left to stand at roomtemperature for 3 months. Further, the dried product of this sol had arefractive index of 1.87.

Example 4 For Preparation of Modified Metal Oxide Sol

The same operation as in Preparation Example 1 was carried out exceptthat the stannic oxide colloid as the component A-1-1 in PreparationExample 1 was changed to 1,237.7 g of the stannic oxide colloid as thecomponent A-1-3, and the aqueous medium containing an alkalicomponent-containing diantimony pentaoxide colloid and an oligomerthereof as the component B-1-1 was changed to 277.8 g of the aqueousmedium containing an alkali component-containing diantimony pentaoxidecolloid and an oligomer thereof as the component B-1-2 so that theweight ratio of (B)/(A) as calculated as metal oxides would be 0.1.

The obtained high concentration modified stannic oxide aqueous sol had aspecific gravity of 1.226, a pH of 7.92, a viscosity of 3.1 c.p. and aconcentration of 22.0 wt % as calculated as metal oxides, and wasstable.

While 9 liters of methanol was gradually added to 227 g of the abovehigh concentration modified stannic oxide aqueous sol, water wasdistilled off by a rotary evaporator under reduced pressure at a liquidtemperature of at most 30° C. to obtain 160 g of a modified stannicoxide methanol sol having water in the aqueous sol replaced withmethanol. This sol had a specific gravity of 1.084, a pH of 8.0 (mixturewith water in an equal weight), a viscosity of 1.1 c.p., a concentrationof 30.5 wt % as calculated as metal oxides, a water content of 0.68 wt %and particle sizes of from 10 to 15 nm as observed by an electronmicroscope. This sol showed a colloidal color and had a hightransparency, and it was free from e.g. precipitates, white turbidityand thickening and was stable, even after left to stand at roomtemperature for 3 months. Further, the dried product of this sol had arefractive index of 1.92.

Example 5 For Preparation of Modified Metal Oxide Sol

Step (a): 500 kg of pure water was added to 9.16 kg (containing 1.62 kgas calculated as ZrO₂) of a zirconium oxychloride aqueous solution(containing 17.68 wt % as calculated as ZrO₂) having zirconiumoxychloride (ZrOCl₂.8H₂O) dissolved in pure water with stirring, 0.40 kgof 35% hydrochloric acid was further added, and then 270 kg (containing10.8 kg as SnO₂) of the alkaline stannic oxide aqueous sol prepared inA-1-2 was added, and stirring was continued for 10 minutes. The mixedliquid was a sol having a ZrO₂/SnO₂ weight ratio of 0.15, showing acolloidal color and having favorable transparency. The prepared mixedliquid was subjected to a heat treatment at 95° C. for 5 hours withstirring to obtain 779.2 kg of a stannic oxide-zirconium oxide compositesol. This sol had an SnO₂ concentration of 1.38 wt %, a ZrO₂concentration of 0.21 wt % and a concentration of SnO₂+ZrO₂ of 1.59 wt%.

Step (b): 779.2 kg of the stannic oxide-zirconium oxide composite solobtained in Step (a) was gradually added with stirring to 68.83 kg(containing 1.24 kg as calculated as Sb₂O₅) of the aqueous mediumcontaining an amine-containing diantimony pentaoxide colloid and anoligomer thereof obtained in B-1-2 and mixed in a ratio ofSb₂O₅/(SnO₂+ZrO₂)=0.1.

Step (c): The aqueous medium obtained in Step (b) was stirred at atemperature of from 20 to 30° C. for 1 hour.

Step (d): The mixed sol-like slurry obtained in Step (c) was passedthrough a column packed with a hydroxyl group form anion exchange resinto remove anion (Cl⁻) contained in the sol. Then, the sol was aged byheating at a temperature of from 90 to 95° C. for from 2 to 3 hours toobtain a modified stannic oxide-zirconium oxide composite sol. This solwas a sol having a specific gravity of 1.011, a viscosity of 2.9 c.p.and a pH of 10.58 and having favorable transparency.

The obtained modified stannic oxide-zirconium oxide composite aqueoussol (diluted liquid) was concentrated by a filtration apparatus with anultrafilter membrane with a molecular weight cutoff of 100,000 to obtain64.7 kg of a high concentration modified stannic oxide-zirconium oxidecomposite aqueous sol. This sol had a specific gravity of 1.233, aviscosity of 4.8 c.p., a pH of 9.75 and a total metal oxideconcentration of 22.1 wt % and was stable.

While 1,200 kg of methanol was gradually added to 50 g of the above highconcentration modified stannic oxide-zirconium oxide composite aqueoussol, water was distilled off by a rotary evaporator under reducedpressure at a liquid temperature of at most 30° C. to obtain 30.8 kg ofa modified stannic oxide-zirconium oxide composite methanol sol havingwater in the aqueous sol replaced with methanol. This sol was subjectedto filtration to adjust the concentration, and the obtained modifiedstannic oxide-zirconium oxide composite methanol sol had particle sizesof 12 nm as observed by an electron microscope, a specific gravity of1.086, a viscosity of 3.2 c.p., a pH of 8.81 (mixture with water in anequal weight), a concentration of 30.4 wt % as calculated as metaloxides, and a water content of 0.37 wt %. This sol showed a colloidalcolor and had a high transparency, and it was free from e.g.precipitates, white turbidity and thickening and was stable, even afterleft to stand at room temperature for 3 months. Further, this sol had arefractive index of 1.87.

Example 6 For Preparation of Modified Metal Oxide Sol

Step (a): 500 kg of pure water was added to 13.6 kg (containing 2.4 kgas calculated as ZrO₂) of a zirconium oxychloride aqueous solution(containing 17.68 wt % as calculated as ZrO₂) having zirconiumoxychloride (ZrOCl₂.8H₂O) dissolved in pure water with stirring, 0.59 kgof 35% hydrochloric acid was further added, and then 396 kg (containing16.0 kg as SnO₂) of the alkaline stannic oxide aqueous sol prepared inA-1-4 was added, and stirring was continued for 10 minutes. The mixedliquid was a sol having a ZrO₂/SnO₂ weight ratio of 0.15 and a pH of1.72, showing a colloidal color and having favorable transparency. Theprepared mixed liquid was subjected to a heat treatment at 95° C. for 5hours with stirring to obtain 910.2 kg of a stannic oxide-zirconiumoxide composite sol. This sol had an SnO₂ concentration of 1.75 wt %, aZrO₂ concentration of 0.26 wt % and a concentration of SnO₂+ZrO₂ of 2.01wt %.

Step (b): 910.2 kg of the stannic oxide-zirconium oxide composite solobtained in Step (a) was gradually added with stirring to 102 kg (1.84kg as Sb₂O₅) of the aqueous medium containing an amine-containingdiantimony pentaoxide colloid and an oligomer thereof obtained in B-1-2and mixed in a weight ratio of Sb₂O₅/(SnO₂+ZrO₂)=0.1.

Step (c): The aqueous medium obtained in Step (b) was stirred at atemperature of from 20 to 30° C. for 1 hour.

Step (d): The mixed sol-like slurry obtained in Step (c) was passedthrough a column packed with a hydroxyl group form anion exchange resinto remove anion (Cl⁻) contained in the sol. Then, the sol was aged byheating at a temperature of from 90 to 95° C. for from 2 to 3 hours toobtain a modified stannic oxide-zirconium oxide composite sol.

The mixed sol-like slurry obtained in Step (c) was passed through acolumn packed with a hydroxyl group form anion exchange resin in step(d) to remove anions (Cl⁻) contained in the sol. Then, the sol was agedby heating at a temperature of from 90 to 95° C. for from 2 to 3 hoursto obtain a modified stannic oxide-zirconium oxide composite sol. Thissol was a sol having a specific gravity of 1.012, a viscosity of 3.0c.p. and a pH of 10.78 and having favorable transparency.

The obtained modified stannic oxide-zirconium oxide composite aqueoussol (diluted liquid) was concentrated by a filtration apparatus with anultrafilter membrane with a molecular weight cutoff of 100,000 to obtain69.5 kg of a high concentration modified stannic oxide-zirconium oxidecomposite aqueous sol. This sol had a specific gravity of 1.284, aviscosity of 5.0 c.p., a pH of 10.19 and a total metal oxideconcentration of 26.1 wt % and was stable.

While 1,255 kg of methanol was gradually added to 50 kg of the abovehigh concentration modified stannic oxide-zirconium oxide compositeaqueous sol, water was distilled off by a rotary evaporator underreduced pressure at a liquid temperature of at most 30° C. to obtain36.9 kg of a modified stannic oxide-zirconium oxide composite methanolsol having water in the aqueous sol replaced with methanol. This sol wassubjected to filtration to adjust the concentration, and the obtainedmodified stannic oxide-zirconium oxide composite methanol sol hadparticle sizes of 13 nm as observed by an electron microscope, aspecific gravity of 1.086, a viscosity of 4.2 c.p., a pH of 8.92(mixture with water in an equal weight), a concentration of 30.3 wt % ascalculated as metal oxides, and a water content of 0.33 wt %. This solshowed a colloidal color and had a high transparency, and it was freefrom e.g. precipitates, white turbidity and thickening and was stable,even after left to stand at room temperature for 3 months. Further, thissol had a refractive index of 1.92.

Example 7 For Preparation of Modified Metal Oxide Sol

Step (a): 191.6 g (containing 50 g as SnO₂) of the acidic aqueous solobtained in A-1-2 was diluted to 8 wt % with pure water.

Step (b): The stannic oxide aqueous sol obtained in Step (a) was addedwith stirring to 500 g (containing 10 g as Sb₂O₅+SiO₂) of the aqueousmedium containing a diantimony pentaoxide-silica composite colloid andan oligomer thereof of B-2-1 and mixed in a weight ratio of (B)/(A) ascalculated as metal oxides of 0.2.

Step (c): The aqueous medium obtained in Step (b) was aged by heating ata temperature of from 90 to 95° C. for 2 hours.

The obtained modified stannic oxide aqueous sol (diluted liquid) wasconcentrated by a filtration apparatus with an ultrafilter membrane witha molecular weight cutoff of 50,000 at room temperature to obtain 472 gof a high concentration modified stannic oxide aqueous sol. This sol hada pH of 1.87, a viscosity of 2.3 c.p. and a concentration of 12.7 wt %as calculated as metal oxides and was stable.

While 9 liters of methanol was gradually added to 472 g of the abovehigh concentration modified stannic oxide aqueous sol, water wasdistilled off by a rotary evaporator under reduced pressure at a liquidtemperature of at most 30° C. to obtain 190 g of a modified stannicoxide methanol sol having water in the aqueous sol replaced withmethanol. This sol had a specific gravity of 1.091, a pH of 2.06(mixture with water in an equal weight), a viscosity of 1.6 c.p., aconcentration of 30.3 wt % as calculated as metal oxides, atransmittance of 68%, a water content of 0.9 wt % and particle sizes offrom 10 to 15 nm as observed by an electron microscope. This sol showeda colloidal color and had a high transparency, and it was free from e.g.precipitates, white turbidity and thickening and was stable, even afterleft to stand at room temperature for 3 months. Further, the driedproduct of this sol had a refractive index of 1.8.

Example 8 For Preparation of Modified Metal Oxide Sol

Step (a): 500 kg of pure water was added with stirring to 9.16 kg (1.62kg as ZrO₂) of a zirconium oxychloride aqueous solution (17.68% as ZrO₂)having zirconium oxychloride (ZrOCl₂.8H₂O) dissolved in pure water, and0.40 kg of 35% hydrochloric acid was further added, and then 270 kg(10.8 kg as SnO₂) of the alkaline stannic oxide aqueous sol prepared inA-1-2 was added, and stirring was continued for 10 minutes. The mixedliquid was a sol having a ZrO₂/SnO₂ weight ratio of 0.15, showing acolloidal color and having favorable transparency.

The prepared mixed liquid was subjected to a heat treatment at atemperature of 95° C. for 5 hours with stirring to obtain 779.2 kg of astannic oxide-zirconium oxide composite sol. The sol had a SnO₂concentration of 1.38 wt %, a ZrO₂ concentration of 0.21 wt % and aconcentration of SnO₂+ZrO₂ of 1.59 wt %.

Step (b) 1,111 g (containing 50 g as SnO₂+ZrO₂) of the stannicoxide-zirconium oxide composite sol obtained in Step (b) was graduallyadded with stirring to 1,050 g (containing 10 g as Sb₂O₅+SiO₂) of theaqueous medium containing a diantimony pentaoxide-silica compositecolloid and an oligomer thereof obtained in B-2-1 and mixed in a weightratio of (Sb₂O₅+SiO₂)/(SnO₂+ZrO₂) of 0.2.

Step (c): The aqueous medium obtained in Step (b) was stirred at atemperature of from 20 to 30C for 1 hour.

Step (d): The mixed sol-like slurry obtained in Step (c) was passedthrough a column packed with a hydroxyl group form anion exchange resinto remove anions (Cl⁻) contained in the sol. Then, the sol was aged byheating at a temperature of from 90 to 95° C. for from 2 to 3 hours toobtain a modified stannic oxide-zirconium oxide composite sol. This solwas a sol having a pH of 8.00 and having favorable transparency.

The obtained modified stannic oxide-zirconium oxide composite aqueoussol (diluted liquid) was continuously passed through a column packedwith a cation exchange resin and a column packed with an anion exchangeresin and then concentrated by a filtration apparatus with anultrafilter membrane with a molecular weight cutoff of 50,000 to obtain517 g of a high concentration modified stannic oxide-zirconium oxidecomposite aqueous sol. This sol had a pH of 3.15 and a total metal oxideconcentration of 11.6 wt % and was stable.

While 8 liters of methanol was gradually added to 517 g of the abovehigh concentration modified stannic oxide-zirconium oxide compositeaqueous sol, water was distilled off by a rotary evaporator underreduced pressure at a liquid temperature of at most 30° C. to obtain 190g of a modified stannic oxide-zirconium oxide composite methanol solhaving water in the aqueous sol replaced with methanol. This sol wassubjected to filtration to adjust the concentration, and the obtainedmodified stannic oxide-zirconium oxide composite methanol sol hadparticle sizes of from 10 to 15 nm as observed by an electronmicroscope, a specific gravity of 1.024, a viscosity of 2.5 c.p., a pHof 2.77 (mixture with water in an equal weight), a transmittance of 79%,a concentration of 25.0 wt % as calculated as metal oxides and a watercontent of 0.76 wt %. This sol showed a colloidal color and had hightransparency, and it was free from e.g. precipitates, white turbidityand thickening and was stable, even after left to stand at roomtemperature for 3 months. Further, this sol had a refractive index of1.8.

Example 9 For Preparation of Modified Metal Oxide Sol

18.1 g of glycolic acid was added and dissolved in 1.2 kg of themodified stannic oxide-zirconium oxide composite methanol sol obtainedin Preparation Example 5 and left at rest overnight. The obtained solhad a specific gravity of 1.090, a viscosity of 2.9 c.p., a pH of 5.7and a total metal oxide concentration of 30.1 wt % and was stable.

Example 10 For Preparation of Modified Metal Oxide Sol

31.5 g of glycolic acid was added and dissolved in 2.18 kg of themodified stannic oxide-zirconium oxide composite methanol sol obtainedin Preparation Example 6 and left at rest overnight. The obtained solhad a specific gravity of 1.086, a viscosity of 2.8 c.p., a pH of 5.8and a total metal oxide concentration of 30.1 wt % and was stable.

Example 11 For Preparation of Modified Metal Oxide Sol

237 g of tartaric acid and 88 g of diisopropylamine were gradually addedin this order with vigorously stirring to 33.0 kg of the highconcentration modified stannic oxide-zirconium oxide composite obtainedin Step (d) of Preparation Example 5, and stirring was continued for 1hour. While about 400 liters of methanol was gradually added to theobtained sol, water was distilled off by a rotary evaporator underslightly reduced pressure at a liquid temperature of at most 80° C. toobtain 22 kg of a modified stannic oxide-zirconium oxide compositemethanol sol having water in the aqueous sol replaced with methanol. Theobtained sol had a specific gravity of 1.102, a viscosity of 3.1 c.p., apH of 8.2 and a total metal oxide concentration of 30.7 wt % and wasstable.

Example 12 For Preparation of Modified Metal Oxide Sol

148 g of tartaric acid and 35 g of diisopropylamine were gradually addedin this order with vigorously stirring to 28.5 kg of the highconcentration modified stannic oxide-zirconium oxide composite obtainedin Step (d) of Preparation Example 6, and stirring was continued for 1hour. While about 400 liters of methanol was gradually added to theobtained sol, water was distilled off by a rotary evaporator underslightly reduced pressure at a liquid temperature of at most 80° C. toobtain 22 kg of a modified stannic oxide-zirconium oxide compositemethanol sol having water in the aqueous sol replaced with methanol. Theobtained sol had a specific gravity of 1.100, a viscosity of 2.0 c.p., apH of 7.5 and a total metal oxide concentration of 30.6 wt % and wasstable.

Example 13 For Preparation of Modified Metal Oxide Sol

5.9 g of glycolic acid was added and dissolved in 1.3 kg of the modifiedstannic oxide-zirconium oxide composite methanol sol obtained inPreparation Example 11 and left at rest overnight. The obtained sol hada specific gravity of 1.094, a viscosity of 1.6 c.p., a pH of 5.2 and atotal metal oxide concentration of 30.3 wt % and was stable.

Example 14 For Preparation of Modified Metal Oxide Sol

3.9 g of glycolic acid was added and dissolved in 0.76 kg of themodified stannic oxide-zirconium oxide composite methanol sol obtainedin Preparation Example 12 and left at rest overnight. The obtained solhad a specific gravity of 1.094, a viscosity of 1.4 c.p., a pH of 4.8and a total metal oxide concentration of 30.4 wt % and was stable.

Example 15 For Preparation of Modified Metal Oxide Sol

The same operation as in Preparation Example 1 was carried out exceptthat the stannic oxide colloid as the component A-1-1 in PreparationExample was changed to 1,401 g of the stannic oxide colloid as thecomponent A-1-5, and the aqueous medium containing an alkalicomponent-containing diantimony pentaoxide colloid and an oligomerthereof as the component B-1-1 was changed to 277.8 g of the aqueousmedium containing an alkali component-containing diantimony pentaoxidecolloid and an oligomer thereof as the component B-1-2 so that theweight ratio of (B)/(A) as calculated as metal oxides would be 0.1.

The obtained high concentration modified stannic oxide aqueous sol had apH of 11.1, a viscosity of 2.5 c.p. and a concentration of 13.5 wt % ascalculated as metal oxides and was stable.

While 9 liters of methanol was gradually added to 392 g of the abovehigh concentration modified stannic oxide aqueous sol, water wasdistilled off by a rotary evaporator under reduced pressure at a liquidtemperature of at most 30° C. to obtain 173 g of a modified stannicoxide methanol sol having water in the aqueous sol replaced withmethanol. This sol had a specific gravity of 1.091, a pH of 8.7 (mixturewith water in an equal amount), a viscosity of 1.0 c.p., a concentrationof 30 wt % as calculated as metal oxides, a water content of 1.9 wt %and particle sizes of from 10 to 15 nm as observed by an electronmicroscope. This sol showed a colloidal color and had a hightransparency, and it was free from e.g. precipitates, white turbidityand thickening and was stable, even after left to stand at roomtemperature for 3 months. Further, the dried product of this sol had arefractive index of 1.95.

Example 16 For Preparation of Modified Metal Oxide Sol

The same operation as in Preparation Example 1 was carried out exceptthat the stannic oxide colloid as the component A-1-1 of PreparationExample 1 was changed to 5,373 g of the stannic oxide colloid as thecomponent A-1-5, and the aqueous medium containing an alkalicomponent-containing diantimony pentaoxide colloid and an oligomerthereof as the component B-1-1 was changed to 503 g of the aqueousmedium containing an alkali component-containing diantimonypentaoxide-silica composite colloid and an oligomer thereof as thecomponent B-2-1, so that the weight ratio of (B)/(A) as calculated asmetal oxides would be 0.2.

The obtained high concentration modified stannic oxide aqueous sol had aspecific gravity of 1.222, a pH of 3.2, a viscosity of 2.1 c.p. and aconcentration of 19.8 wt % as calculated as metal oxides and was stable.

While 21 liters of methanol was gradually added to 2,160 g of the abovehigh concentration modified stannic oxide aqueous sol, water wasdistilled off by a rotary evaporator under slightly reduced pressure toobtain 1,360 g of a modified stannic oxide methanol sol having water inthe aqueous sol replaced with methanol. This sol had a specific gravityof 1.083, a pH of 6.8 (mixture with water in an equal amount), aviscosity of 1.2 c.p., a concentration of 30 wt % as calculated as metaloxides, a water content of 2.0 wt % and particle sizes of from 10 to 15nm as observed by an electron microscope. This sol showed a colloidalcolor and had high transparency, and it was free from e.g. precipitates,white turbidity and thickening and was stable, even after left to standat room temperature for 3 months. Further, the dried product of this solhad a refractive index of 1.95.

Comparative Preparation Example 1

In this Example, a titanium oxide methanol sol to be used forComparative Examples was prepared.

587.5 g (159.8 g as TiO₂) of titanium tetrachloride (manufactured bySumitomo Sitix Corporation, containing 27.2 wt % as TiO₂, Cl content of32 wt %) and 2,608.5 g of water were put in a jacketed separable flaskof 3 L made of glass to prepare 3,196 g of a titanium chloride aqueoussolution (containing 5.0 wt % as TiO₂). To this aqueous solution, 50 gof 28% aqueous ammonia was added with stirring with a glass stirringrod, and the aqueous solution was hydrolyzed at 95° C. for 10 hours toobtain agglomerates of titanium oxide colloidal particles having primaryparticle sizes of from 4 to 8 nm.

The slurry of agglomerates of titanium oxide colloidal particles wassubjected to filtration under reduced pressure with a 5B filter paper,and an excess electrolyte was removed by washing with about 40 L ofwater to obtain 620 g of a wet cake of titanium oxide. The obtained wetcake was dispersed in 2,576 g of water, 8.0 g of isopropylamine wasadded thereto to make the dispersion alkaline, and the dispersion waspassed through a column packed with 200 ml of an anion exchange resin(AMBERLITE IRA-410, manufactured by Organo Corporation), to obtain 3,890g of an alkaline titanium oxide aqueous sol. This sol was concentratedunder reduced pressure by a rotary evaporator to obtain 1,070 g of aconcentrated alkaline titanium oxide aqueous sol. To the obtained sol,12.1 g of tartaric acid and 26.1 g of diisopropylamine were added withstirring. Then, while 25 L of methanol was gradually added to the sol,water was distilled off under reduced pressure to replace the aqueousmedium with methanol to prepare 775.2 g of a titanium oxide methanolsol. The obtained methanol sol had a specific gravity of 0.970, aviscosity of 4.5 mPa·s, a pH (1+1) of 8.98, an electrical conductance of1,600 μs/cm, a TiO₂ concentration of 20.2 wt % and a water content of3.4 wt %.

Preparation of Coating Liquid

Example 1

To a glass reactor equipped with a magnetic stirrer, 105.3 parts byweight of γ-glycidoxypropyl trimethoxysilane corresponding to theabove-described component A was added, and 36.8 parts by weight of 0.01N hydrochloric acid was dropwise added thereto over a period of 3 hourswith stirring. After the completion of the dropwise addition, stirringwas carried out for 0.5 hour to obtain a partial hydrolysate ofγ-glycidoxypropyltrimethoxysilane. Then, 397.8 parts by weight of themodified stannic oxide composite methanol sol covered withalkylamine-containing diantimony pentaoxide (containing 30.5 wt % ascalculated as all the metal oxides) obtained in the above PreparationExample 1, 65 parts by weight of butyl cellosolve and 4.2 parts byweight of aluminum acetylacetonate as a curing agent were added to 142.1parts by weight of the above-described partial hydrolysate ofγ-glycidoxypropyltrimethoxysilane and sufficiently stirred, followed byfiltration to prepare a coating liquid.

Formation of Cured Film

The above coating composition was coated on a commercially availablepolycarbonate plate having a refractive index nd=1.59 by spin coating,followed by heat treatment at a temperature of 120° C. for 2 hours tocure the coating film. The evaluation results are shown in Table 1.

Example 2

The same operation as in Example 1 was carried out except that 397.8parts by weight of the modified stannic oxide composite methanol solcovered with alkylamine-containing diantimony pentaoxide (containing30.5 wt % as calculated as all the metal oxides) of Preparation Example2 was used instead of the modified stannic oxide composite methanol solcovered with alkylamine-containing diantimony pentaoxide of PreparationExample 1 used in Example 1. The evaluation results are shown in Table1.

Example 3

The same operation as in Example 1 was carried out except that 397.8parts by weight of the modified stannic oxide composite methanol solcovered with alkylamine-containing diantimony pentaoxide (containing30.5 wt % as calculated as all the metal oxides) of Preparation Example3 was used instead of the modified stannic oxide composite methanol solcovered with alkylamine-containing diantimony pentaoxide of PreparationExample 1 used in Example 1. The evaluation results are shown in Table1.

Example 4

The same operation as in Preparation Example 1 was carried out exceptthat 22.3 parts by weight of tetraethoxysilane and 77.9 parts by weightof γ-glycidoxypropylmethyldiethoxysilane corresponding to component Awere used instead of γ-glycidoxypropyltrimethoxysilane corresponding tocomponent A used in Example 1, 2.6 parts by weight of aluminumacetylacetonate and 0.5 part by weight of ammonium perchlorate were usedas curing agents. The evaluation results are shown in Table 1.

Example 5

The same operation as in Example 2 was carried out except that 74.2parts by weight of γ-glycidoxypropyltrimethoxysilane and 31.1 parts byweight of γ-glycidoxypropylmethyldimethoxysilane corresponding tocomponent A were used instead of γ-glycidoxypropyltrimethoxysilanecorresponding to component A. The evaluation results are shown in Table1.

Example 6

The same operation as in Example 3 was carried out except that 74.2parts by weight of γ-glycidoxypropyltrimethoxysilane and 31.1 parts byweight of γ-glycidoxypropylmethyldimethoxysilane corresponding tocomponent A were used instead of γ-glycidoxypropyltrimethoxysilanecorresponding to component A. The evaluation results are shown in Table1.

Example 7

The same operation as in Example 1 was carried out except that 397.8parts by weight of the modified stannic oxide methanol sol covered withalkylamine-containing diantimony pentaoxide (containing 30.5 wt % ascalculated as all the metal oxides) of Preparation Example 4 was usedinstead of the modified stannic oxide methanol sol covered withalkylamine-containing diantimony pentaoxide of Preparation Example 1used in Example 1.

Example 8

The same operation as in Example 1 was carried out except that 397.8parts by weight of the modified stannic oxide-zirconium oxide compositemethanol sol covered with alkylamine-containing diantimony pentaoxide(containing 30.5 wt % as calculated as all the metal oxides) ofPreparation Example 5 was used instead of the modified stannic oxidemethanol sol covered with alkylamine-containing diantimony pentaoxide ofPreparation Example 1 used in Example 1.

Example 9

The same operation as in Example 1 was carried out except that 399.0parts by weight of the modified stannic oxide-zirconium oxide compositemethanol sol covered with alkylamine-containing diantimony pentaoxide(containing 30.4 wt % as calculated as all the metal oxides) ofPreparation Example 6 was used instead of the modified stannic oxidemethanol sol covered with alkylamine-containing diantimony pentaoxide ofPreparation Example 1 used in Example 1.

Example 10

The same operation as in Example 1 was carried out except that 400.3parts by weight of the modified stannic oxide methanol sol covered withdiantimony pentaoxide-silica composite colloid (containing 30.3 wt % ascalculated as all the metal oxides) of Preparation Example 7 was usedinstead of the modified stannic oxide methanol sol covered withalkylamine-containing diantimony pentaoxide of Preparation Example 1used in Example 1.

Example 11

The same operation as in Example 1 was carried out except that 485.2parts by weight of the modified stannic oxide-zirconium oxide compositemethanol sol covered with diantimony pentaoxide-silica composite colloid(containing 25.0 wt % as calculated as all the metal oxides) ofPreparation Example 8 was used instead of the modified stannic oxidemethanol sol covered with alkylamine-containing diantimony pentaoxide ofPreparation Example 1 used in Example 1.

Example 12

The same operation as in Example 1 was carried out except that 403.1parts by weight of the modified stannic oxide-zirconium oxide compositemethanol sol covered with alkylamine-containing diantimony pentaoxide(containing 30.1 wt % as calculated as all the metal oxides) ofPreparation Example 9 was used instead of the modified stannic oxidemethanol sol covered with alkylamine-containing diantimony pentaoxide ofPreparation Example 1 used in Example 1.

Example 13

The same operation as in Example 1 was carried out except that 397.8parts by weight of the modified stannic oxide-zirconium oxide compositemethanol sol covered with alkylamine-containing diantimony pentaoxide(containing 30.5 wt % as calculated as all the metal oxides) ofPreparation Example 10 was used instead of the modified stannic oxidemethanol sol covered with alkylamine-containing diantimony pentaoxide ofPreparation Example 1 used in Example 1.

Example 14

The same operation as in Example 1 was carried out except that 395.1parts by weight of the modified stannic oxide-zirconium oxide compositemethanol sol covered with alkylamine-containing diantimony pentaoxide(containing 30.7 wt % as calculated as all the metal oxides) ofPreparation Example 11 was used instead of the modified stannic oxidemethanol sol covered with alkylamine-containing diantimony pentaoxide ofPreparation Example 1 used in Example 1.

Example 15

The same operation as in Example 1 was carried out except that 396.4parts by weight of the modified stannic oxide-zirconium oxide compositemethanol sol covered with alkylamine-containing diantimony pentaoxide(containing 30.6 wt % as calculated as all the metal oxides) ofPreparation Example 12 was used instead of the modified stannic oxidemethanol sol covered with alkylamine-containing diantimony pentaoxide ofPreparation Example 1 used in Example 1.

Example 16

The same operation as in Example 1 was carried out except that 400.3parts by weight of the modified stannic oxide-zirconium oxide compositemethanol sol covered with alkylamine-containing diantimony pentaoxide(containing 30.3 wt % as calculated as all the metal oxides) ofPreparation Example 13 was used instead of the modified stannic oxidemethanol sol covered with alkylamine-containing diantimony pentaoxide ofPreparation Example 1 used in Example 1.

Example 17

The same operation as in Example 1 was carried out except that 399.0parts by weight of the modified stannic oxide-zirconium oxide compositemethanol sol covered with alkylamine-containing diantimony pentaoxide(containing 30.4 wt % as calculated as all the metal oxides) ofPreparation Example 14 was used instead of the modified stannic oxidemethanol sol covered with alkylamine-containing diantimony pentaoxide ofPreparation Example 1 used in Example 1.

Example 18

The same operation as in Example 1 was carried out except that 403.1parts by weight of the modified stannic oxide methanol sol covered withalkylamine-containing diantimony pentaoxide (containing 30.1 wt % ascalculated as all the metal oxides) of Preparation Example 15 was usedinstead of the modified stannic oxide methanol sol covered withalkylamine-containing diantimony pentaoxide of Preparation Example 1used in Example 1.

Example 19

The same operation as in Example 1 was carried out except that 403.1parts by weight of the modified stannic oxide methanol sol covered withalkylamine-containing diantimony pentaoxide-silica composite colloid(containing 30.1 wt % as calculated as all the metal oxides) ofPreparation Example 16 was used instead of the modified stannic oxidemethanol sol covered with alkylamine-containing diantimony pentaoxide ofPreparation Example 1 used in Example 1.

Comparative Example 1

The same operation as in Example 1 was carried out except that 643.6parts by weight of the titanium oxide methanol sol (containing 20.2 wt %as TiO₂) prepared in Comparative Preparation Example 1 was used insteadof the sol used in Example 1. The evaluation results are shown in Table1.

Comparative Example 2

The same operation as in Example 1 was carried out except that 433.3parts by weight of a tin oxide methanol sol covered with fine tungsticoxide-stannic oxide composite particles (containing 30.0 wt % asSnO₂+WO₃) as disclosed in JP-A-3-217230 was used instead of the sol usedin Example 1. The evaluation results are shown in Table 1.

Comparative Example 3

The same operation as in Example 1 was carried out except that 433.3parts by weight of a titanium oxide-stannic oxide-zirconium oxidecomposite oxide colloid methanol sol (containing 30.0 wt % asTiO₂+SnO₂+ZrO₂) as disclosed in JP-A-10-310429 was used instead of thesol used in Example 1. The evaluation results are shown in Table 1.

Comparative Example 4

The same operation as in Example 1 was carried out except that 650.0parts by weight of a colloidal silica (methanol sol, solid content: 20%,average particle size: 15 nm) was used instead of the sol used inExample 1. The evaluation results are shown in Table 1.

Physical properties of an optical element having a cured film, obtainedin each of Examples and Comparative Examples, were measured by thefollowing measurement methods.

(A) Scratch Resistance Test

The surface of each cured film was rubbed with a steel wool # 0000,whereupon scratch resistance was visually evaluated in accordance withthe evaluation standards (A), (B) and (C), wherein the degree of scratchmarks increased in the order of (A), (B) and (C).

(2) Presence or Absence of Interference Fringes

The optical element having a cured film was visually observed under afluorescent lamp and evaluated in accordance with the evaluationstandards (A), (B) and (C), wherein (A) designates no substantialinterference fringes observed, and in the order of (B) and (C), theoccurrence of interference fringes increased.

(3) Adhesion Test

On the cured film, 100 crosscut sections with spaces of 1 mm wereformed, and an adhesive tape (cellophane tape, product manufactured byNICHIBAN Co., Ltd.) was intimately adhered to the crosscut sections andthen rapidly peeled, whereupon the presence or absence of peeling of thecured film after the adhesive tape was peeled was examined.

(4) Warm Water Resistance Test

The optical element was immersed in a warm water of 80° C. for 2 hours,whereupon the optical element was subjected to the same adhesion test asdescribed above.

(5) Transparency Test

The optical element was visually examined under a fluorescent lamp in adark room to see if there was any fogging on the cured film, inaccordance with the evaluation standards (A), (B), and (C), wherein (A)designates substantially no fogging observed, and in the order of (B)and (C), the degree of fogging increased.

(6) Weather Resistance Test

The obtained optical element was subjected to outdoor exposure for 1month, and the change in the appearance of the optical element afterexposure was visually evaluated.

TABLE 1 Warm Scratch Inter- water resis- ference Adhe- resis- Trans-Weather tance fringes sion tance parency resistance Example 1 A A GoodGood A Good Example 2 A A Good Good A Good Example 3 A A Good Good AGood Example 4 A A Good Good A Good Example 5 A A Good Good A GoodExample 6 A A Good Good A Good Example 7 A A Good Good A Good Example 8A A Good Good A Good Example 9 A A Good Good A Good Example 10 A A GoodGood A Good Example 11 A A Good Good A Good Example 12 A A Good Good AGood Example 13 A A Good Good A Good Example 14 A A Good Good A GoodExample 15 A A Good Good A Good Example 16 A A Good Good A Good Example17 A A Good Good A Good Example 18 A A Good Good A Good Example 19 A AGood Good A Good Comparative B A Good Peeled B Blued Example 1Comparative B A Good Partially A Slightly Example 2 peeled yellowedComparative A to B A Good Good A to B Good Example 3 Comparative A CGood Good A Good Example 4

The cured films of Examples 1 to 19 of the present invention wereexcellent in scratch resistance, absence of interference fringes,adhesion, warm water resistance, transparency and weather resistance.However, the cured films of Comparative Examples 1 and 2 wereinsufficient in view of scratch resistance, warm water resistance,transparency and weather resistance, and the cured film of ComparativeExample 4 was unfavorable since interference fringes were observed.Further, the cured film of Comparative Example 3 was not particularlyinferior practically, but was slightly inferior to the cured films ofExamples 1 to 19.

INDUSTRIAL APPLICABILITY

The sol of the present invention is particularly useful as a componentto improve refractive index, dyeability, chemical resistance, waterresistance, moisture resistance, light resistance, weather resistance,abrasion resistance, etc. when a hard coat film is formed on a plasticlens, and it can be used for various applications.

By applying the sol of the present invention to the surface of e.g.organic fibers, textile products or paper, the flame resistance,anti-slip properties, antistatic properties, dyeability, etc., of suchmaterials, can be improved. Further, the sol is useful as a bindingagent for e.g. ceramic fibers, glass fibers and ceramics. Further, bymixing the sol with e.g. a coating agent or an adhesive, the waterresistance, chemical resistance, light resistance, weather resistance,abrasion resistance, flame resistance, etc., of a cured coating film ofthe coating agent or the adhesive, will be improved. Further, the sol isuseful commonly as a surface treating agent for e.g. metal materials,ceramic materials, glass materials and plastic materials. Further, it isuseful also as a catalyst component.

The optical element having a cured film made of the coating compositionof the present invention is useful for not only lenses for eyeglasses,but also lenses for cameras, window glasses for automobiles and opticalfilters for liquid crystal display or plasma display devices.

The present invention is based on a Japanese Patent Application No.2002-350762 (filed on Dec. 3, 2002), a Japanese Patent Application No.2002-350763 (filed on Dec. 3, 2002), a Japanese Patent Application No.2003-097786 (filed on Apr. 1, 2003), a Japanese Patent Application No.2003-097789 (filed on Apr. 1, 2003), a Japanese Patent Application No.2003-161080 (filed on Jun. 5, 2003) and a Japanese Patent ApplicationNo. 2003-161087 (filed on Jun. 5, 2003), and their entireties are herebyincluded by reference.

1. A process for producing a modified metal oxide sol, comprising:producing a stannic oxide aqueous sol comprising stannic oxideparticles, wherein sizes of the stannic oxide particles are from 4 to 50nm, and a SnO₂concentration of from 0.5 to 50 wt %; hydrothermallytreating the stannic oxide aqueous sol at a temperature of from 100 to300° C.; mixing the hydrothermally treated stannic oxide aqueous solwith an aqueous solution of an oxyzirconium salt having a concentrationof from 0.5 to 50 wt % as calculated as ZrO₂; heating the obtained mixedliquid at a temperature of from 60 to 100° C. for from 0.1 to 50 hoursto prepare a stannic oxide-zirconium oxide composite aqueous sol havingparticle sizes of from 4 to 50 nm; mixing the heated stannicoxide-zirconium oxide composite aqueous sol with an aqueous mediumcomprising Sb₂O₅ colloidal particles comprising an alkylamine, anoligomer thereof or a mixture thereof; aging the aqueous mixture of thestannic oxide-zirconium oxide composite aqueous sol and aqueous mediumcomprising Sb₂O₅ colloidal particles comprising an alkylamine at atemperature of from 20 to 300° C. for from 0.1 to 50 hours; andcontacting the aged aqueous mixture with an anion exchanger to removeanions present in the sol; wherein a weight ratio of ZrO₂/SnO₂ in thestannic oxide-zirconium oxide composite aqueous sol is from 0.05 to0.50, an alkylamine/Sb₂O₅ molar ratio in the Sb₂O₅ colloidal particlescomprising an alkylamine is from 0.02 to 4.00, and a weight ratio ofSb₂O₅/SnO₂+ZrO₂) in the aqueous mixture of the stannic oxide-zirconiumoxide composite aqueous sol and aqueous medium comprising Sb₂O₅colloidal particles comprising an alkylamine is from 0.01 to 0.50,calculated as metal oxides.